No fix but adding my two cents. For me issues occurs with thunderbolt docks (2 tested Cable matters, and Pluggable dock). MBP 16" i9 32 GB new less than 2 months old. For reference the same docks plugged into my Linux laptop work fine. Once flicking starts Unplugging HDMI cable or removing the dock connection causes a kernel panic and reboot I was able to reduce the flicking by never closing the MBP, and installing an app to prevent sleeping. This reduced the issue, but it comes back typically during video conferencing. I can't find the reference at the moment, but there is another thread that indicates this is a bug in Big Surs implementation of Thunderbolt which occurs with 4k or higher monitors connected via HDMI. I was hopping the recent 11.6 upgrade would sneak in a fix, but no such luck yet. Hope this helps someone. As others have noted changing the resolution to scaled, randomly adjusting supported refresh rates works sometimes (not consistent).