Since this video seemed low on details, I did some research: The overall issue seems to be that Australian law now requires that, in order to work in Australia, a phone must be able to make emergency calls on the 4G/5G bands that are used in Australia. There isn't really a good way to tell the capabilities of a phone when it connects to the network, so they maintain a blocklist for phone models that don't support this.

The problem is that it turns out there's a lot of 4G/5G phones that fall back to 2G/3G for emergency calls, or calls in general. Owners of these phones thought they were new enough to not be affected by the 3G shutdown, but are being required to get new phones. There are also some phones that don't support emergency calling out of the box, but can be modified to work by owners by manually modifying SIM settings to force enable volte for example. Since the device block list is by model, someone who modified their phone to work is still locked out.

AU Government incompetence in my opinion.