Since the upgrade to 89, I have a problem with Youtube that, judging by Google results, nobody else on earth has. If I click on a video, it starts to play normally but as soon as the page finishes loading the video stops and returns to the start of the video. I have to click the play button to get it to play, which it then does without any issues. The same problem happens when videos are part of one of Youtube's playlists. Video starts, page finishes loading, video stops and goes back to the start. I've been through too many Google searches, tried about:config changes, policy changes, toggling autoplay in Youtube, installed extensions that supposedly control autoplay. Nothing works. This was not a problem with 88 when I first had it. When 89 first appeared, I was so frustrated with the wasteful display setup that I uninstalled Firefox and went back to 88; this was when the Youtube issue first appeared. I upgraded back to 89 when I found out how to turn off Proton (because my Bookmark menu shouldn't mostly wasted vertical space) but the Youtube problem persists. Somebody, please tell me how to fix this.