Oh wow. I had this 'flickering screen' issue on my brand new laptop with #Ubuntu 22.04 and thought I had found the bug describing it (which involved adding magical processor config to Grub as a workaround).
Except that their described flickering was much worse than what I experience.
I just now notice that it is the Brightness dial going up and down by itself. Yea, the UI slider is actually moving by itself like the crazy compass on The Flying Dutchman.