Is this too hot while idle? Or while watching videos on ungoogled chromium

Sensors: System Temperatures: cpu: 64.6 C mobo: 16.8 C gpu: amdgpu temp: 54.0 C
Fan Speeds (RPM): N/A gpu: amdgpu fan: 1517

A temp in the 60’s it fairly normal for a light to moderate workload on a modern CPU.

Chances are your ungoogled chromium video is being software decoded which puts some load on the cpu.