Well I decided to upgrade to Debian testing last night on my desktop here, just for fun. It seems fine.
Xfce4-screensaver wasn't in bullseye so I had an old locally compiled version installed, which may have been the cause of some video problems. Replaced with the debian build.
A broken bash completion script I had removed came back and was annoying until I remembered what I'd done.
Old searx install didn't work, neither did latest searxng install script from git. Too many python errors for me, so I gave up and ran the docker container instead. That was the only frustrating part.
Skyrim runs more smoothly and amdgpu hasn't crashed yet. It had been getting bad lately, locking up during video playback sometimes (maybe once a week) in the past month or two. I think perhaps running the newest kernels with the old mesa was a bad combination.
I ran out of disk space on the EFI partition during install, but it recovered no problem.
Other than that no problems so far.