macOS Sonoma Boot Failures(github.com) |
macOS Sonoma Boot Failures(github.com) |
However, this is such a great write up, very thorough with root cause, mitigations etc.
Keep up the good work!
Like, you press Launchpad, and it just ... doesn't open. sometimes. This kind of rancid stuff you would expect on Windows (i.e. after upgrade to Windows 11, half our laptops can't right click on the desktop sometimes) but it never used to happen on OS X.
We've gotten to point with the huge number of abstraction layers (and now AI as well) that troubleshooting what causes system to do what it did, has become so unwieldily difficult to diagnosis.
I had Ubuntu installed in a second partition and it refuses to boot ever since I installed 12.5.1 on it.
>Why? I can tell you why: because Apple hates display modeset flicker, and switching modes between ProMotion on/off causes a modeset flicker, so of course they made it so that is stored in nvram somewhere and applied when the screen is turned on during early boot, so when macOS boots it doesn't have to flicker again.
>And they didn't test it with older OS bootloaders, so display handoff/init just fails catastrophically with those when this mode is enabled.
Ran into one recently that was high-rez graphical. It needed a USB mouse to change critical settings because the tab order for the onscreen widgets didn't work.
Anyone responsible for creating graphical EFI config screens should stop writing software for the good of humanity.
As an analogy this would be sort of like rebooting the OS in place while preserving all the running apps, network state and USB connections without resetting anything.
These kinds of things are possible, but have lots of corner cases.
I thought this wasn't really a problem anymore.
Thank god someone does. Hate how jank plugging monitors in just because some engineers thought “meh, good enough”.
Don’t think I should be seeing things flicker anywhere in my life with the computing power we have today and yet many consider visual nails on a chalkboard as acceptable.
I've come to embrace the flicker and the systemd messages. It's just a boot, it's in the order of seconds in this day and age, I can't even tell you what the initial reason for my obsession was.
The first reason that comes to mind is battery life. That's probably the most broadly applicable use case.
But also, if I was still doing e.g. frontend web development, I would want to confirm that my css animations looked nice at 60 hz.
Edit: My first use case is likely wrong, thank you to replies for reminding me Apple uses adaptive refresh down to 1 hz.
These might seem unrelated, but:
* There's a `defaults set` setting that allows you to speed up the transition animation length from 1 second to 0.5 second, which is huge because that transition is extremely poorly implemented (it leaves the windows on the workspace that you're leaving activated until the transition is complete, so you start typing and it's on the other screen you can't even see any more) and VERY SLOW
* That setting only works if the refresh rate is 60Hz, and it completely fails to do anything if ProMotion is on, because for some reason the animation length isn't programmed to handle the different refresh rates.
So having ProMotion off relieves frustration.
Would be nice if I could force my MBP to run at 100Hz for PAL Amiga/C64 emulation - or even better if emulators could/would change the refresh rate at least when running full-screen.
(Actually, since Sonoma, I can manually set it to 50Hz, but there's no fixed refresh rate options above 60Hz, just 'Pro Motion'. Previously, the refresh rate setting seemed missing entirely on my M1 MBP)
Admittedly rather niche use case.
...and I bet that's exactly the attitude Apple had when implementing things, which lead to this mess.
The computer was connected to a Thunderbolt Display during the update which I assume had the same effect of changing the refresh rate to something other-than-ProMotion that the linked article mentions. I had to do a DFU restore from another Mac and then run the macOS Sonoma installer from USB, which thankfully detected the existing install and did an in-place upgrade, preserving all of my data. Nothing else worked.
I also wasted far too much time trying to get the DFU restore to work before discovering that you cannot use a Thunderbolt cable — it has to be done using a plain USB-C cable, otherwise the Apple Configurator simply won't detect the other Mac.
It's obvious that it's some incompatibility between 13.2 base system and 13.6 install. Apple quality is atrocious these days. One would have thought they would test the most basic scenarios before releasing their x.6 software.
And worse of all, there's no official (or even unofficial, at least I wasn't able to find one) way to create USB boot installer without another Mac or to DFU restore Mac without another Mac. Do they think I live in Apple Store? I don't have other Mac. I was able to DFU restore with libimobiledevice, god bless its creator, but it really should not happen. Windows or Linux are so much more transparent compared to macOS.
Conversely windows, just got a USB stick in the drawer I can boot off.
It goes further than that, on many motherboards even a failed firmware update can be fixed through a random USB stick from the drawer, you just need the right BIOS file to put in it.
How far we’ve fallen.
Linux as well. Will probably work better than windows on older hardware
I'll need to get an external drive, back everything up, then do a DFU restore on my M1 Max MBP to get it upgraded to Sonoma.
Good luck with that.
If there's a documented problem that affects your hardware model and the given software versions, they're extremely unlikely to try to charge you for anything.
Just today I had an experience that was so Kafkaesque it felt like a mean spirited prank, and because they never fuck up this badly, I had no contingency plan for one of the times it matters a lot.
Any advice on how to get the “we fix things for loyal customers by doing what’s required” people on the phone would be appreciated, but based on the runaround, infinite hold Ferris wheel the primary support line apparently is now, I’m not getting my hopes up.
Maybe the newest group of programmers and engineers are dealing with a very complicated code base? Maybe no one fully understands everything involved until something breaks?
On the software side, I tend to tolerate more security risk (within reason) to delay updates until a consensus emerges that they’re robust, because I’m not a high value target to anyone north of “script kiddy” and run a tight ship on the easy stuff, so the EV of an abruptly unusable work machine vs. getting pwned weighs heavily relative to winding up in the crosshairs of anyone sophisticated enough to exploit a recent CVE. My online banking is properly 2-fac’d, if anyone wants to read my browser history or email and cares enough to go ti that trouble, I’ll want them that I’m not important enough for it to be worth the trouble.
This would clearly change if my work went back to having demanding security requirements, but it doesn’t just now.
It’s really the customer service, fulfillment, Apple Store experience (it used to feel like stepping into the least stressful room in the mall and now it’s a zoo).
Do you really think users want graphic mode selection on boot? What percent of Mac users have alternate bootloaders or even know what that means.
A lot of commenters need to do some time in the proverbial trenches and support a fleet of devices at a large company. See if users really care about the things you think they do.
> Once System Firmware is updated to the macOS Sonoma version, if the display is configured to a refresh rate other than ProMotion, that system will no longer be able to boot into older macOS installs nor Asahi Linux correctly. This includes recovery mode when those systems are set as the default boot OS, and also System Recovery at least until the next subsequent OS upgrade.
That can and will absolutely affect regular users, even if they don't 'care' about it or 'know what it means'.
No, that seems pretty super-user to me. The average user goes forward in versions, not back, and rarely has two at the same time.
This issue can occur to any user who wants to have two macOS versions for whatever reason. Not that extraordinary especially between creative professionals
Issues on Sonoma appear most often on dual-booting macs: https://support.apple.com/en-us/HT208891
Ventura upgrades can also bite you if your display refresh rate is set to anything other than ProMotion, for unclear reasons.
The doc is on the Asahi Linux wiki because their developers discovered this issue, but it's not unique to Asahi. In fact, running the Asahi Linux installer can detect whether your mac will be affected by this issue, even if you ultimately choose not to install Asahi Linux. See the article for details.
Any time I start a new video project now, I save it instantly because Command+S still works, but if it opens the Save As dialog then it frequently won’t.
https://trixter.oldskool.org/2006/02/02/computing-myth-1-sof...
Well dang, I just upgraded yesterday, too. Fingers crossed that nothing breaks...
Something stinks in this thing.
Or does that mean wait for 14.2?
Definitely shoddy QA on Apple's part. Also, your sample size is too small. Everyone works differently and it takes a certain set of settings/workflows to trigger this compatibility issue.
I would have expected a Thunderbolt cable to be required, if either was. This is quite surprising to me. Usually, the more capable (higher bandwidth) cable works if one isn’t supported. I’ll hope to remember this is I ever find myself reviving a bricked Mac in the future.
My understanding is that all complaint USB USB-C cables should work for USB 2.0, even USB4/TB4 cables, but active TB3 cables might not hook up the USB 2.0 pins.
> A supported USB-C to USB-C charge cable, such as the one sold by Apple (may not be available in all countries or regions) or a supported USB-A to USB-C cable
> The USB-C cable must support both power and data. Thunderbolt 3 cables aren’t supported.
[1] https://support.apple.com/guide/apple-configurator-mac/reviv...
Anw, I followed a video by Mr. Macintosh and managed to get mine up and running, whew.
See Also: entering bootloader mode in android devices
I would really advise against having anything connected to the Macbook during upgrades, except the charger...
In my mind, when we pay that ridiculous Apple premium on RAM and storage, we pay for excellent quality in SW/HW. They also need to deliver that quality.
(I think it is ridiculous that the system works in that way, especially for a company that hasn’t needed investors in over a decade, but it is what it is.)
I was affected by this and like many users the problem was fixed after replacing the I/O board. In my case, I did it myself using a $10 part from Ebay since the machine was well out of warranty at that point.
https://forums.macrumors.com/threads/macos-big-sur-update-br...
https://forums.macrumors.com/threads/macos-big-sur-update-br...
https://forums.macrumors.com/threads/macos-big-sur-update-br...
But my Google Pixel phone used to brick itself all the time, I think twice in the two years I had it.
About two weeks ago I'm sitting in a hotel room with the air on bed with the lid open. I grab it by the screen to slide it closer to me and the screen shatters from the light pressure of my finger.
There are instances of both these things happening to the Air all over the internet. At first I really liked the M1 Air, but it has now proven too unreliable for me.
Premium™
Shame to hear the build quality in the latest is so poor.
On Sonoma I can select 24, 25, 30, 50, 60, 100, 120 Hz, in addition to "Variable (40-120 Hz) refresh rates for my LG C2 display. When selecting 50 or 100 Hz, scrolling in (PAL) C64 emulation in VICE becomes much smoother, but not perfect. However, when I enable variable refresh rate and switch to fullscreen mode, VICE can perfectly synchronize the refresh rate and scrolling/animations become butter smooth.
I do recall my last motherboard had an option for a splash which was centered in a black screen, so you could basically display it at native resolution with no stretching and it would look great and seamless. I wish every motherboard had that splash option now.
Here's a play-by-play scenario.
1) Grandma is prompted to update to Sonoma, and so she does.
2) But note that the installer does not update the recovery partition.
3) Laptop reboots, and grandma sees an Apple logo for exactly 2 seconds, and then the screen goes black. Manually rebooting results in the same thing, every time.
4) Grandma now tries to roll up her sleeves and see if she can fix it. She googles around, and discovers that the she should be able to get into the Recovery OS and maybe fix things there... but when she tries to do that, same thing: apple logo for 2 seconds and then black screen.
How did I come up with this play-by-play? Well, because today I was said grandma.
Where does this involve the average user going back in versions of their on volition? That's the whole point of why this bug is horrible: you get no say in the matter. You upgrade to Sonoma, and depending on your refresh rate, you can't boot into your OS. Wanna use the Recovery OS? Too bad: that's too old to know to use a functioning refresh rate settings (because the installer left the old Recovery OS version in place), and instead it uses whatever was set in NVRAM (or similar) from when you last configured the refresh rate.
Wasted today using another MacBook to update the Recovery OS via DFU (using Apple Configurator), and now I'm reinstalling Sonoma from that recovery, and praying that this will unbrick my laptop for work tomorrow.
Normal people don't care about it, talk about it, or think about it, but may come to rely on it - or have it used by a 'Genius' when something stops working. It affects them.
Turning off the screen can take a long time, but it is possible that putting up a "hot black" screen would be better than flicker if you had to do it.
It's not possible (well, it's very difficult) to do this on an Apple Silicon Mac; once there's an update you can always apply it from another Mac, like the steps on this page do, and your data is still there. With Intel Macs it's possible.
The definition of "bricked" is not set in stone; a lot of what a normal person would consider "bricked" (doesn't turn on, or turns on to an unresponsive black screen, and no magic sequence of button presses can reset it to working order) could be fixed by a power user with the right equipment, software, and knowledge.
In this case, it requires fairly expensive equipment (another $2.5-10k device), somewhat easy to acquire software, and the appropriate set of instructions, to overwrite the device's broken firmware with a working copy; you don't have to open up the device and plug a JTAG adapter, but using the DFU protocol is very similar to that, since in both cases you're writing directly to the firmware under control of an external device. This is not like "BIOS FlashBack" and similar on non-Apple PCs, in which the device can rewrite its firmware by itself from a common USB stick.
(Also, about data loss: a device with removable storage could get bricked without any data loss, and fixed also without any data loss, simply because the data storage is separated from the firmware and from most of the hardware. It's Apple's insistence on non-removable storage which risks losing data when something else makes the device fail to boot.)
Of course they do. They’re just secretive in general, and keep communications edited. Compared to the word salad of modern companies on social media, I find it refreshing. Just fix the problem, issue replacements for those affected and move on quietly.
I've run into such horrific bugs during pretty normal use that I don't think this anymore.
These days it's just a bunch of wannabes trying too hard to be him.
A few minutes of access to one, not ownership of it, and hardly any system requirements on it.
> It's Apple's insistence on non-removable storage which risks losing data when something else makes the device fail to boot.
That's actually not the reason. All storage is removable if you just desolder it. It's because the storage is encrypted and you can't extract the keys.
I had to spend 6+ hours on the phone over multiple days with a senior tech support staff to make it happen, but at least it was eventually resolved and I didn't pay anything for it. Obviously it wasn't a documented problem because we troubleshooted everything possible before replacement.
You paid 6+ presumably stressful hours of your time. That sounds like a crazy high price to me that you should be able to bill them for.
I wonder whether they could've done it faster if they were required to reimburse you for the time and nerves you had to spend to get them to fulfill their (assuming you were within warranty) law-mandated responsibility of providing you with a product that works as described.
How did you even get to the point of talking to them on the phone? When I last had a problem (extreme instability up to full crashes when RAM pressure is high, which is apparently a problem with every single ARM Mac out there) they wanted me to come into an authorized store as the first thing.
I eventually caved in and just bought a machine with bigger RAM. My god, I can't imagine spending several hours over several days turning the device off and on, resetting NVRAM and re-installing the system ...
/troll
I can't say I've heard of that happening to people on Linux at all other than maybe early days of Xorg. Damage (reversible or otherwise) to hardware is extraordinarily rare on Linux, I can only think of it happening during the very early days of EFI and only under very specific conditions.
This is similar to macOS, Windows, or even FreeBSD releases. I haven’t seen any Linux distribution that has such comprehensively coordinated releases. Between systemd and the Linux kernel, I’m not sure it would be possible.
Many distros have good documentation, but, in my experience, far too often the bulk of it is in out of date wikis or forums. Perhaps this is out of date thinking and I’ve missed the train in the past 10 years.
As a counterpoint, OpenWRT has been good, but their main “product”, imho, is LuCI. Lower level issues often require vendor specific forums.
Of course, whether that's valid is at minimum a question of actual frequency of problems and relative impact and effort to fix, but from a perspective of optics and emotions I understand the reaction.
For one example on top of my head, sometimes I can't adjust the brightness of the monitor in the Macbook using the Notification Center (it is grayed out), but if I open the "Settings -> Displays" I can do it. Never found a solution for it after searching for a while, so I just gave up.
Or the fact that I can't enable retina or font smoothing in my 1440p monitor, so the fonts looks ugly (I got used eventually, but they still looks worse than Windows or Linux in the same monitor). I used a workaround in the past using "Better Display" to create a 4k framebuffer that was downscaled to 1440p, but this was so slow and also prone of other issues so eventually I just got used to the ugly fonts.
Another one: I have a TouchBar Macbook (again, this is a work-issued laptop), but I just want it to work as a normal keyboard: show the Function keys, if I press Fn show the shortcuts. Yep, doesn't work: while you can do this, pressing Fn while pressing some of the shortcuts in the TouchBar doesn't work. This is especially infuriating because one of the shortcuts that doesn't work is the brightness one. Go back to the first issue and you can see why this drive me mad sometimes.
My perception: current Mac is an oversized iPad without touchscreen
GP of this thread links to a post arguing that Apple is going out of their way to avoid just that during the boot sequence.
An animation that looks slick at 120 fps might look too fast/slow/complex/whatever on a common 60 hz screen. So if I was still doing this sort of development, I'd prefer to be working on a 60 hz monitor.
I've been advocating (and using) high refresh displays for over two decades and I find your reasoning preposterous. Downgrading to crappy 60 Hz monitor for nothing.
If we want to compare apples to apples, then we compare:
Mac with macOS updates installed regularly, and only those provided by Apple. Non-Apple apps get dropped in /Applications like they should be. If there's an installer that asks for root access, you might get boned.
Linux preinstalled with OS updates installed regularly, and only those provided by the vendor. Apps that don't come with the OS's package manager should be installed somewhere under $HOME, and never installed systemwide as root.
Sure, if you have a Mac and disable SIP (or whatever it's called nowadays) and start mucking around with files in /System or whatever, because you want to install some mod that does something cool, you might have a bad time. Same as if you decide that screwing around in /lib on a Linux machine is a good idea.
But if we actually compare these two apples, I suspect the Linux one would have fewer problems.
No, worse, with more device incompatibilities, manual fiddling, arcane settings, and so on to make things work.
>Sure, if you have a Mac and disable SIP (or whatever it's called nowadays) and start mucking around with files in /System or whatever, because you want to install some mod that does something cool, you might have a bad time.
Sure, but I'm not talking about that. With Linux you often have a bad time trying to make basic, but not distro configured, functionality to work.
If you mean various third party resellers then of course, it's just a run of the mill shop that happens to sell Apple products, a completely different experience.
Apple Store is a totally different shebang, if those are not owned by Apple it would be a major news story for lots of people.
And if they are owned by apple I don't see why their employees can not see bug reports.
Where? Do you have any examples?
The whole battery gate saga. Touch Bar. The 2013 Mac Pro [1].
[1] https://www.theverge.com/2017/4/4/15175994/apple-mac-pro-fai...
But they never have the common sense to release statements like "hey, the latest MacOS update might brick some systems so we're pulling the updated until we can do further testing and patching, if you've been affected by the bug already go to a Apple store and have it fixed for free".
Hiding entails ignoring the problem. They're not doing that. Their track record is to fix it. Not every action needs an accompanying tweet and blog post.
There was that LG CD-ROM drive which treated a CD-RW command (which it should ignore or reject since it's not a CD-RW drive) as a firmware upload command. When a newer Linux kernel started using that command, these drives got bricked (source: https://lwn.net/Articles/55537/ and https://web.archive.org/web/20041204072839/http://www.mandra...).
https://www.phoronix.com/news/UEFI-rm-root-directory
https://www.kernel.org/doc/html/latest/filesystems/efivarfs....
Most users will just take their machine in to the Apple Store when this kind of thing happens, rather than try to fix it themselves.
You're right that it's not ideal, but it certainly makes it a lot _less_ inconvenient than being completely stuck forever (as most non-highly-technical people would be if they had to follow instructions on forums to fix Linux).
I suppose I'm failing to see the need for a public statement if you've fixed the problem and provide service to those affected. Nobody can pull the faulty update anymore. And it's not like someone with a bricked device is more likely to see a PR statement than seek out support.
[1] https://osxdaily.com/2023/07/11/apple-pulls-rapid-response-u...
Did you read what I wrote above? "if you buy preinstalled"
If you install Linux on an ordinary "Windows-certified" computer, you will have problems. If you install an alternative OS on a Macbook, you will have exactly the same problems.
And did you understand my point? Buying preinstalled isn't a cure-all, only ensures that the bundled hardware drivers are compatible and configured. That's a pretty low bar.
It doesn't cover doing stuff with third party devices (which on the Mac 99% of the time it works every time).
Not to mention even the bundled-hardware doesn't always work even if you buy pre-installed (like the laptop not sleeping properly for example).
I agree that this is not tolerable. However my devices from Purism have a reliable sleep and other functionality out of the box.
> third party devices
Check Linux compatibility before buying and they will work reliably. Works for me.
Presumably ProMotion is a specific mode that the display/display controller/... first needs to be set to. If you start out in anything other than that and then switch to it later in the boot process, you'd get that blank screen for a second, and Apple avoids that by writing the startup mode to non-volatile memory.
Otherwise they could also just always start out in ProMotion mode – but then you'd get flicker every time you (re)boot into any other mode, like 60 Hz for people who prefer that.
There’s very likely still a scan out rate determined by the maximum refresh rate, just that the source can delay the next frame if it’s not ready yet.
In other words, e.g. 120 Hz and 144 Hz of VRR aren’t the same even when displaying a 60 Hz signal at the moment – the faster signal would have more pauses and a higher signal rate.
I made a small experiment about raf https://codepen.io/mmis1000/pen/qBxqgLr and it always looks uniform regardless I am on a 60, 120, 160 fps screen. (It would blink crazily if you put it in the middle of two screen with different refresh rate, because it can't be in two refresh rate at same time)
Erit: okay, it looks non uniform only in safari. Clap, clap, clap, Apple…
Did some quick Googling to make sure I wasn't just out of the loop on this, as far as I can tell they are not the same: https://github.com/whatwg/html/issues/5025
> As such, on their 120hz devices, requestAnimationFrame is throttled to 60hz, whereas CSS animations run at 120hz.
Please let me know if I am misunderstanding, it has been a few years since I've done this type of work.
The last time I dared to request a troubleshooting for the terrible lockups (sometimes down to the touchpad click not responding directly) that I now believe are caused by swapping (and are present on every ARM Mac I've used), I was offered by the official Apple website to make an appointment at Gravis, an authorized reseller and then perhaps also authorized repair provider.
But Apple Store I think is owned by Apple and people there actually work at Apple. Also if Apple Store was the same franchise thing as authorized resellers then I don't see why there would be so few Apple Stores around the world.
Also wow. I didn't have this particular touchpad issue with my M1 mac yet. I do have a bunch of gripes with Apple about other issues though. Just a couple days ago noticed notification center was using 100% CPU and draining battery. Only because I wanted to check time in another timezone using world clock widget. Trying to edit the widget and select a different city locked up the entire thing with all the other widgets. Dumpster fire.
Even if what happens is that they are just a favoured franchise.
https://upload.wikimedia.org/wikipedia/commons/0/05/Award_BI...
https://liveusb.files.wordpress.com/2010/05/awardbios-firstb...
And the simplified crap with tabs that often came with prebuilt PCs but later seems to have spread to others too:
https://cdn.staticneo.com/a/Intel_Sandy_Bridge_Z68_P67/S%20B...
Long-time Thinkpad users scoff at that ... while the figure of a duck suddenly enters their minds..
(Yes: I clearly remember my pre-USB thinkpad having a graphical BIOS with windows, icons, and a duck-shaped mouse cursor).
BIOSes of the time were all written in highly-optimised Asm, and I suspect those little "easter eggs" they added were because the programmers knew they had enough space left over to put some more fun stuff in.
There was also AMI WinBIOS that provided a GUI, but I remember it being much less featureful than other BIOSes of the time with a TUI and didn't like mobos that used it, so in that case they may have sacrificed functionality for appearance.
I've had a GUI BIOS setup on almost every PC I've owned since the first 486 I built back in 1993.
UEFI actually lets you provide both touchscreen-capable bells&whistles gui, and a text UI for the frankenstein VT-UTF8 standard (essentially, VT-220 compatible with UTF-8, kinda like linux console) - all in mostly one codebase.
There's a standard UI description language which is used to specify menus, options and values (and how they are written into nvram), which is then interpreted by text mode interface driver (enabled when you connect over serial port) and graphic mode interface driver (where you can drop all sorts of graphical bells & whistles).
It's also how you can integrate menus from add-on cards into firmware setup.
Besides, there’s nothing to prevent you having a nice graphical boot configuration while still having a text version as a fallback (which is exactly what Intel Macs do)
That said yes, there’s no reason why there shouldn’t be a low rez textual fallback.
> Seems a bit overkill for something people rarely use.
Okay, but a lot less so than a full GUI with mouse and thousands of colors, like many motherboards have gone to.
Got into the temps, realized that the CPU fan had been plugged into an AUX fan header instead of the CPU header.
Fan was spinning, wouldn't have thought to check if the EFI wasn't crashing.
I'm completely joking of course. I completely agree with you, I miss text-only mode. The modern Dell one stinks, the Asus one stinks...I have no data, but I'd be shocked if Gigabyte or ASRock were any good... :(
Many applications have a way of synchronizing their drawing loop to the monitor refresh rate, for example; ProMotion must be doing something clever to support them, or they'd just force the refresh rate to 120 Hz.
macOS also supports variable refresh rate external monitors these days (via both DisplayPort and HDMI); I'm not sure if that would be labeled "ProMotion" in the display settings, but in any case there are things that can go wrong there, and having a way to opt out of that at the HDMI/DisplayPort signal level (and not just fixing the frame rate at the GPU level while driving the external link under VRR) seems like a good idea.
I'm guessing it probably has to do with compliance with the original VESA standard, or whatever the completely basic support of multiple resolutions and refresh rates in all monitors is called.
The bootstrap of booting a system always ends up relying on the most basic supported things to start with (such as 640x480@60Hz using the VESA standard) and then upping it from there.
You’re either in macOS or booted in its recovery partition.
So, yes, fixed 120 Hz and 120 Hz with VRR and without any skipped frames might well be the same mode to a GPU, but it also might be a different one, requiring a mode switch. I don't know how Apple has implemented it.
But in any case, for the bug at hand it's irrelevant: Apple's ProMotion uses a refresh rate of 120 Hz, so switching between that and 60 Hz is definitely a mode switch.
Now Apple’s bootloader is actually a tiny macOS. As much as I don’t like the complexity this brings, I do strongly approve of a boot environment that supports proper input devices and video. My iMac Pro’s (intel, non-macOS-based bootloader) bootloader drops keyboard inputs when typing my long passphrase because I type too fast for it. The Mx macs no longer have this problem.
