I’m a YouTube premium subscriber. Just yesterday I found myself opening a private window to watch a video with ads, rather than letting the algorithm know I was watching the video on my account. Even if I remove the video from my watch history, YouTube can’t help itself. You make a great point on stale content and the overall enshittification is becoming intolerable.
Wow. In my case the YT recommendations system works very well, only suggesting things similar to what I've already watched and liked.
I would never use YouTube in incognito mode or logged out... it's positively garish and loud with garbage.
Pay a little extra for YouTube Premium Family and you can silo your interests to different Google profiles. I have work and home like this basically. Coding, AI, etc on one, cars, retro games on another. No ads.