Running Firefox on a relatively new Arch install, using xorg with a AMD GPU, I have xf86-video-amdgpu installed (but the same issue occurs when it is not installed).

After about 30 seconds of use, the entire desktop freezes and I am either sent to SDDM to log in again, or the screen turns completely black and I have to physically power cycle the machine. This is very annoying, I cannot get work done.