I think a big part is that the headline is antithetical to what Firefox's brand has been, but doesn't make it clear that this is due to an update. Even just saying "Firefox: The newest Data Collection, Advertising Browser" would be better. Otherwise, people who are familiar with Firefox but not the newest update will read the headline and think, "What? No it isn't." Downvote
I agree, components of the video description and the video itself also seem a bit sensationalist even if the information is factually correct. "cabal" for example.