> Debian is stable,

Stable in Linux language is a synonym for OLD. Don't let any stable OSes near any hardware that is newer than the release, and you'll be fine.

Linux 6.12 was released back in 2024, which is several months earlier than the hardware you have. So the reasonable expectation is that there is a high chance that fixes for it won't be in yet.

And use the builtin AMD drivers, you shouldn't have to touch those assuming other choices were done ok.