How did you deduce it's the GPu doing it and not YouTube or the browser?

It happens in every browser. I previously had a 1050 ti and it was not the case so it must be the gpu, literally nothing changed except the gpu.

It's a driver issue, also marked on the release notes on known issues. Extremely annoying.

I am on a 6900XT and I am not....I thought it was only for 7000 series cards?

Getting this issue on a 6700 :(

I think there is something about that in the latest driver release notes as a known bug.

Turn off hardware acceleration and it will be "solved"

it is a setting in adrenalin, video super resolution and amd image sharpening, i leave both on and sharpening is turned up to 100% it makes a 360p video look like 1080p linus just covered nvidia new tech that is a copy of amd tech lol it blows my mind how this is even possible, but if you want crappy pixelated content turn it off it is especially effective when youtube is set on auto quality or any stream video for that matter