I’ve been using a really nice extension the past couple months called unhook [0] that gives a lot of control over the YouTube UI. I’ve disabled shorts, the homepage, related videos, comments, etc. and now I only see videos I have subscribed to. Much more useful (I subscribed for a reason!) and much less time wasted. Just thought I’d share in case it helps anyone!
I block recommendation sections on some site with the ublock element picker (like the "recommendations" stackoverflow puts in the right column from their other sites, completely unrelated to the current page or search terms).
I never got round to trying that with Youtube, this seems a better solution.
[0]: https://unhook.app/