Happening to me also (on Quest 2). However, this was not occurring early today after I'd updated the Oculus App. It's only started doing it this evening when I'm using artificial lighting. So could be related to the tracking sampling frequency colliding with (imperceptible) strobing of the mains powered room lights. I've tried selecting all Auto/50/60Hz tracking sampling rates (my power is 50Hz) to no avail. I'll try it again tomorrow in natural light.
What appears to be happening is that the viewpoint is shifting by several feet for a single frame, which causes the screen to appear to flash and the audio to cut out as I'm outside the aircraft for a split second, during which time the sim hasn't caught up and switched to external sounds yet. Then I'm back inside before it does. It also resets the mouse cursor position when inside the cockpit making it useless to select switches. Glad I'm not the only one!
Same issue here. Disabling beta channel seems to remove the flickering, but my oculus tray tool then doesn't seem to work anymore.