The trick to improving YouTube recommendations is to regularly prune uninteresting videos and channels. Eventually this should start surfacing videos you're more likely to find interesting.
I've actually hit the end of my recommendation stream on the mobile app after marking dozens of videos with Not Interested. Once this happens it starts recommending videos you've already watched or older videos from creators you've been watching lately.
Personally, I'd love it if you could curate the recommendation system a bit more. I'm never interested in rewatching stuff I've already seen. And the recency bias for recommendations means you're always getting more if what you've recently consumed. I'd like it if more older interests were mixed in. Finally, I'd love to be able to blacklist certain topics and games entirely.
There's so much missed potential with YouTube recommendations.
Some might say that you can still use search, but that has been crippled to include unrelated recommendations after one page of results. Not only that, I want YouTube to help me discover new content. When the recommendation system works and it shows me new kinds of interesting stuff, it's superb. TikTok is eating YouTube's lunch in this regard.
Edit: forgot to mention this. On mobile if you do a recommendation refresh it'll show a New to You filter which you can use to explore more diverse recommendations. I don't know why it's hidden in this manner.