Hello. I also have the issue with random white flashes while on desktop with my 7900XT. Turning off freesync seems to fix it but I want freesync so that's no good. However if you don't need freesync, turning it off could be a working workaround.
Also in a certain game I play in exlusive full screen, I sometimes get kinda similar white flashing in some areas of screen. Not sure if that is related to this or a different thing.
Also heard that Windows feature called MBO might at the root of this issue and disabling it might help. However disabling it seems like a hassle because it needs to be done in registry and don't want to use third party tools to do it. So I haven't tried that.