Hello @ProkopRandacek, I reproduced this issue on my Arch test box and for me the illegal instruction is VMOVQ in /usr/lib32/dri/r600_dri.so. That makes this a mesa 20.0.7 -> 20.1.0 regression where AVX is unconditionally used on hardware that does not support it.
This is being tracked at https://bugs.archlinux.org/task/66972.
Thank you for your help. Simply replacing lib32-mesa with lib32-mesa-git fixed the issue.
Nothing extracted yet.
Steam crashes on start due to Illegal instruction
cpu info & steam console output
I have seen #5164 but steam used to work for a few months on my machine and still works on windows.