Earlier quoted context omitted.
What corporate stuff do you have on your main page? Mine is all pretty much filled with content that matches what I watch.
This seems pretty tautological. What you watch will reflect your reccomendations because there is a causal relationship there, unless you never use youtube for discovery. I alledge that what people spend time watching is more heavily shaped by reccomendations than they are aware of.
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).