I am experiencing the same in Reverb G2. Only when flying at night and only the outside world flickers, in this case the sky. Inside the cockpit everything is fine. The effect gets worse when I switch to external view, then the entire picture starts flickering.
The craziest thing about this is when I turn on cockpit lights (I mostly fly PMDG737 these days) this glitch disappears! It looks like it only appears in very dark scenes.
As others said it’s only visible in the headset. WMR mirror looks fine, same the game mirror on a monitor. I tried to capture it with a mobile but the camera struggles to focus on the lens.