I'm running up-to-date Debian 10 + backports. While using ordinary everyday programs, like webbrowser with video inside, text editors, etc. my visuals suddenly froze a little while, but audio still playing in background. Keyboard still worked, but screen graphics was garbled as show in the attached picture. GPU fan speeded up and down a few times and settled again. I managed to switch to another TTY and dump informations about crash before I rebooted the machine. Note that I often suspend my machine after work.
Created attachment 289601 [details] screen graphics after freeze
Created attachment 289603 [details] dmesg output
Created attachment 289605 [details] xorg log
Created attachment 289607 [details] lsmod amdgpu
Created attachment 289609 [details] basic info
The GPU hung and was reset successfully. Since there is no support for GPU resets in window systems, you'll need to restart your desktop environment. GPU hangs are most likely caused by bugs in the user mode graphics drivers. I'd suggest updating to a newer version of mesa.
I try upgrade to latest available kernel, Mesa, Xorg in Debian testing/bullseye and see if it makes a difference.
after upgrade i have not notice any incidence since. does not mean it is fixed, but closing this for now anyway.