For compatible intel processor’s:
I found that leaving intel extreme tuning utility on in the background even closing out the app out from desktop but not completely exiting it will immediately stop the zwift flickering.
Seems to be very minimal on resources because I was only using 3.9gb of memory in windows 11 with it running in the background.
There did seem to be a slight FPS hit with XTU on while running zwift at the lowest resolution, so might be even less a hit when running it at 4k.
This works on stock default bios settings no modifications.
I’ve never used OBS myself which is another work around I hear.