I don't know how most mullvad users use it, but I've never used their ovpn configurations, and I use it on client devices and not some network gateway. It's not going to affect me one bit. I've considered using it on some network hardware I have that only supports openvpn to give myself network wide benefits of it, but because I often use it on my clients to change IPs, and otherwise cycle through different servers as needed, haven't made that move yet. So even if I wanted to, I'd probably have to do a custom solution which means I can use wireguard anyway.