Same, completely locked up kde plasma and had to do a hard reset.

[drm:amdgpu_job_timedout [amdgpu]] ERROR ring gfx_0.0.0 timeout, but soft recovered [drm:amdgpu_job_timedout [amdgpu]] ERROR ring gfx_0.0.0 timeout, signaled seq=344186197, emitted seq=344186200 [drm:amdgpu_job_timedout [amdgpu]] ERROR Process information: process Vivaldi-Gpu pid 1111641 thread vivaldi-bi:cs0 pid 1111675 GpuWatchdog[1262135]: segfault at 0 ip 00007f20dfcfbbc6 sp 00007f20d4bc14f0 error 6 in libcef.so[7f20db858000+7770000] likely on CPU 6 (core 6, socket 0)