At least that's how it works for my account even though I'm completely uninterested in the guy.
It's gotten to the point where I don't click links simply because I don't want to get spammed.
You are so not interested in him that you a) know his name and b) watch his videos?
If you want to get rid of something you only clicked once, click something you like 2-3 times and it will not be listed in the first results anymore. After some time it will disappear if you really do not watch this kind of content.
This works with and without account.
EDIT: on the other hand, a few days back I accidentally used private browsing on a technical video and got a few of those mythical good ads of the sort that inform you about a genuinely interesting and relevant product you didn't know about. So maybe it's not the worst thing ever.
It's not been blocking youtube ads for me for a week or two.
Yes to the point where looking for content on prehistory can lead to flat earther conspiracy theory rubbish.
Maybe if youtube did not keep you in an etertainment bubble you would find much more music you unexpectedly enjoy from artists or genres you haven't heard of.
For example, when I'm in the mood to watch sailing videos, I don't want to get bombarded with Taylor Swift's latest concert (which I have absolutely no interest in) in the recommendations. My interests don't necessarily align with what's "popular", and anything bubble-less will necessarily have the popularity of something as one of its inputs.
Compare that with news, where some events are important enough that _everyone_ should know about them (COVID-19, for example), local events affect you more, etc. There, the bubble is a hindrance to your situation awareness.
As for music, I mostly use Google Play Music for that, through which I have discovered a lot of new artists.
In general it seems that social media regarding news and politics is almost always toxic and should be avoided.
Twitter in particular is entirely awful because the format prohibits any intelligent discourse.
However, I have refrained from clicking on videos before even if they seemed interesting in the moment, because I don't want to extend my "bubble" in that direction (I've gotten that before). So in my experience, the bubble is actually too easy to extend.