The other day a little modal appeared on the side of youtube.com desktop saying something like, "Curious for new stuff? Explore content that isn't what you usually watch."
It ended up being sorta like an alternate reality. It was all the topics I usually watch, but with different channels I don't normally see at all. In other words, it was as if all the channels I normally watch don't exist, what else would exist to fill the void.
https://i.imgur.com/XIRW4U2.jpeg
When opening videos that are sent to me by others, I always use a private window, so my main account is pretty low "variance".
When I find a creator I like, I do a "fake binge", by queuing all their recent videos and some old ones too and playing them unattended.
I also try to minimize my use of the recommendation sidebar, since it usually shows content related to the current video rather than the more general recommendations of the home page.
When something foreign sneaks its way to my home page, I immediately click "not interested", paying attention to not hover the thumbnail.
Overall, Youtube has got me trained pretty well, but at least I get some nice recommendations out of it, so much so in fact that over half the recommendations I get are usually videos I have already watched (even if Youtube thinks I haven't yet for whatever reason).