I think there are some intersections of interest that make the algorithm hypothesize that you're a certain kind of person. Like if you watch a lot of strength training content, and then you watch one lecture on Heidegger, YouTube is like, oh, we finally figured this guy out, he's a white supremacist or at the very least a gun nut. But if I watch a video about cupcakes, I'll only get a few suggestions about baking, not any associated interests, because cupcakes don't combine with any of my other interests to trigger a stereotype.

I always get those "calming meditation" music videos in recommendations, or "5 Powerful Psalms to Help You Sleep" which is on my homepage right now. Every video is from a different channel named something like "Calming Truth", and I can tell at one glance of the thumbnail that it's one of "those" videos.

I have never, ever watched one, and I always click Not Interested, or Don't Recommend Channel. But they keep on coming. There seems to be an endless supply of them.