Google is known to sabotage non-Chrome browsers and ad-blockers on YouTube, accidentally on purpose at every chance it can get. That's hardly Firefox's fault.

2014: https://news.ycombinator.com/item?id=8606879

2016: https://news.ycombinator.com/item?id=10877810

2018: https://old.reddit.com/r/programming/comments/91i0mc/youtube...

2018: https://news.ycombinator.com/item?id=18697824

2019: https://archive.is/tgIH9

2019: https://www.thurrott.com/google/207371/google-now-forces-mic...

2020: https://news.ycombinator.com/item?id=22422522

2023: https://old.reddit.com/r/youtube/comments/17z8hsz/youtube_ha...

2024: https://news.ycombinator.com/item?id=41379517

2024: https://xcancel.com/brave/status/1870172541907550496

2025: Whatever you're referring to.