I stumbled on this article today, and I think it is relevant here: YouTube, the Great Radicalizer (New York Times, 2018)
Basically, the theory is, that in hopes of getting the users hooked, the YouTube recommendation engine constantly ups the stakes.
This means, recommended videos become more and more "radical" the longer the auto-play function runs. This goes across all topics. The recommendations become more and more "extreme":
Eat healthy >> Vegetarian >> Vegan
Jogging >> Marathon >> Ultra-Marath... See more