I started to experience the case in the title a few days ago. I experience it mostly when using Chrome (unstable) and Vivaldi (also unstable), while with Opera Developer it is less noticeable. I knew no better than turning off hardware acceleration in the most affected browsers, after which the flicker stopped. I also tested this problem under Linux Mint 20.2 and the error was not there. I am using an Nvidia video card with an Xeon processor in my desktop, with 16 GB RAM so far there has been no such error. My questions are: what could be the cause of the screen flicker, why does this error occur in one distribution and not in another, and what can I lose by turning off hardware acceleration in addition to any slower browsing (slower scrolling, etc.) that I didn’t notice?
I noticed this in chromium as well so I moved back to Firefox and working fine.
I am not sure if there was some recent updates in chromium based browser that’s causing it.
I usually use different browsers for different purposes, but it seems good to get back to using Firefox on a daily basis.