Random display freeze AMD TURKS (DRM 2.50.0 / 5.4.0-77-generic, LLVM 11.0.0)

Mon Aug 2 16:54:05 UTC 2021

My display freezes randomly on an Ubuntu 20.04 system with a Radeon AMD 
Turks graphics card.

Before the final freeze I often get warnings by the display suddenly 
turning black and then turning on again.

Not sure if it's the driver or the (cheap) graphics card. How can I find 
out and is there any solution?

Restarting the display manager does not have any effect.