Just updated to Radeon Version 20.9.1. Now the crash caused by moving the render window is gone. So I think we can close this issue. Nevertheless I still have severe issues (Blender 2.90.1). E.g. when simply switching off the screen and turning it on again. Sometimes Blender freezes. Sometimes even the whole system freezes in such case. Then its even not possible to open the Taskmanager anymore ... only hard power off. Very annoying. :-( I'cant recommend the use Radeon RX 570 with Blender at all.

Ok, I've updated from version 19.12.2 to 20.8.3. Unfortunately the issue is still there. I was able to capture the issue with screen recording. See attached:

Attached you can find the requested files. It doesn't really crash. I guess that is the reason why there is no crash file, but the whole machine became completely unusable, with the whole screen blinking black and white once. Before the screen became black/white, I saw the menus optically distorted again. After lets say 15sec I saw the border of the Blender main window and the render window again. I was able to click the red close cross. After a few seconds later Windows asked me if I want to stop the process, and I acknowledged. After that I copied the traces.