I don’t have access to my desktop computer at the moment but i believe it was this rule: https://old.reddit.com/r/youtube/comments/ykana1/how_do_i_disable_youtubes_ambient_mode_permanently/j9khxuh/

I found youtube videos unbearable as well and I found the culprit to be ambient mode in the video settings. I ended up adding a rule in ublock origin to delete the ambient mode stuff regardless of the setting just to make sure ambient mode is disabled in private windows etc.