If you aren't already, I would make sure you're liking/subscribing to things you do want to watch. The algo to me seems primarily driven by thumbsups.

In YT Music especially, this has resulted in some really fantastic recommendations. Being someone who doesn't like most "popular" music (not simply because it's popular, I just think most people have bad taste :-D), I've never had a good experience with music discovery in services until now, and it's gotten on point for me.