so. back in high school and early college I did not have a youtube account. I am now living in a different city than I did then, and all my electronic devices are new. I don't see any way youtube could connect my browsing history to my current self. and this is largely born out in my recommendations: they are what you would expect based on my recent browsing history and not my entirely lifetime browsing history. but. I have extremely unusual music taste. and most of the time, youtube recommends me music based on what I've been listening to recently, like anything else. but if I go back and listen to some music that I listen to a lot in those periods, youtube will suddenly start recommending me other videos I listed to a lot in the same time frame. and this really only happens with music, nothing else.
my only guess as to how this is happening is that my browsing habits were in fact so specific that the algorithm can actually just recognize me. dope.