My videos are also randomly going from 4k to 360p, and having long hitches/pauses. Thats assuming the page loads at all, which may take a few refreshes...and its not an internet/connection related issue.
happening with Firefox with ublock origin.
edit
Honestly, the youtube pages (and only the youtube pages) act slow and laggy like the CPU is running at 100% doing hard number crunching. yet system monitor shows its not even breaking 10% load on the CPU, and that firefox's process isnt even using half that, so it feels like theres something artificially slowing the page down, in retrospect.
Haha that reminds me of a period of my life where I realized it was possible for game devs to detect piracy but instead of making the game say, "not legit copy, cannot play", it would be more subtle and make itself unstable and eventually crash.
I had a pirated copy of RCT3 that would crash regularly after a few hours. Thought maybe that's what was going on, plus it was a good game and worth my money anyways, so I bought a legit copy and installed that.
A few hours into playing, it crashed again.
Oh well, other than the crashing it was still a good game so I don't regret buying it. And I think they sorted it out because my more recent plays didn't see any crashes. I even bought it again on Steam since I'm not entirely sure where the disc is and don't have a drive to read it anyways.