Some Firefox users noticed playback issues on YouTube for several months. These affected high resolution videos only, from 1080p and up. To make matters worse, no clear pattern could be identified.
Some videos played fine, others would stop abruptly when they ran out of buffer.
Oh lol so that was it, yesterday all of a sudden 1440p and 4k videos were unwatchable, it was a stutter fest and thought something was wrong with my gpu.
I’ve noticed that 60fps videos struggle a lot, even at 720p, suspiciously, no issues on chrome