I can attest to this, because I've finally figured out that the algorithm doesn't offer me more of the stuff I've spent a lot of time looking at on YouTube (film analysis, and horror stories). I'm constantly having to clear the recommendations page of the junk that other people find interesting.

YouTube used to be a bit more transparent about why it offered the things it did: other viewers who like whatever you watched, also watched these! I m always filtering out Right wing commentary, and don't get offered much Leftist commentary, and if the algorithm was really going by content I've already engaged with, that's what it would offer me more of. I've had to clear my histories multiple times in the past year.

I know YouTube makes no effort to offer me more of the kinds of videos I'm subscribed to, respond to, or engaging with, (and for some reason will still insist on offering me animal abuse videos, no matter how many times I've said I don't like that sort of content.) I'm starting to think that most of the management buttons I click, mean and do absolutely nothing.