You probably used Nvidia and some outdated distro with a bad DE on top. Not something you should be using. Using X11 is DOA anyway, so you can figure out what was wrong in your case and use better options.
No, AMD. I had issues on the latest Debian, released this summer, with KDE. X11 works perfectly fine. I would be happy with wayland too, if it worked. And in fact I use it on my other device.
The Steam main window did not open, although Steam itself did load in the background. I could work around this by disabling smooth scrolling on web view and some other GPU-related option (I forgot exactly).
But then there was a strange glitch on every single game (both native and Proton-based). Periodically (e.g. every ~10 seconds on some 3D games, on every screen reload on some other) the screen turned black for about 2 seconds.
Then I remembered that I had some issue when I first installed Debian 12 two years, though I forgot which issues exactly, and that I solved them by switching from Wayland to X11.
What DE? And that's with all the latest components as above? I wouldn't use Debian stable for gaming purposes, since it falls behind very quickly. Debian testing / unstable is a better idea, and even then you'd want to install latest amdgpu firmware manually potentially.
