In some open cars (definitely tested and confirmed with open KTM X-Bow) in VR the virtual mirror disappears and re-appears every couple of seconds (sometimes faster). It seems to happen randomly, not a any fixed rate or so. But it happens all the time with those cars, single player and multiplayer. When the ffb meter is activated, it turns off and on together with the virtual mirror. It happens to me and at least 2 other guys from my community and the bug already existed before the june21 update. Never observed it with cars that have a roof. I have a WMR HMD (Reverb G2), another user has it with a Rift S. I have Otterhud running. My graphics options XML is attached. Cheers and thanks for looking at it!
I have the same effect with the FFB-graph window (if activated). Mostly it's not visible but appears for a short time now and then. Only noticed this behaviour with open wheelers (like the X-Bow).