That's not true in my experience, I only subscribe to the type of content I want to watch, but my homepage is still filled with tons of garbage.
God forbid I watch a one-off video on a topic I'm not typically interested in, like woodworking. Current iteration of Youtube algorithm seems to boil down to "oh I see that you watched ONE woodworking video? Well half of your homepage is about woodworking for the next week!". I've started watching videos in incognito mode which I definitely didn't need to do a couple of years ago.
Current Youtube UX is beyond terrible, half the time I can't even find what I'm looking for through search because they arbitrarily cut off real search results to push clickbaity dopamine-sucking content.
If they want me to pay for Premium, they need to do more than just removing ads, the entire experience needs to feel, well, Premium. They could add customization options for the homepage and search results so we can remove shorts and all the "For you" crap, add knobs to tweak recommendations, return dislike counters which were the best way of quickly filtering out terrible/clickbaity/dangerous content. They could even add some power user features like being able to find videos by searching through their indexed transcripts rather than by the title alone.