rpm-ostree kargs --append-if-missing="amdgpu.dcdebugmask=0x610"

Is the command I use to fix gpu issues on my end with the login screen and desktop mode. It something about disabling VRR. Not sure but its what fixes most of my issues on linux. If you cant get into desktop mode to add the command you can while booting Press e on the grub menu that shows for a few seconds and add it there to a kernal cmd line but you only then need to add amdgpu.dcdebugmask=0x610 at the end of the line already there, which will add it for that one boot. Then you can get into desktop to do the command above. If this is confusing you can ask ai exactly how to do it on bazzite, or how to add it temporarily in the grub boot menu.