I just right-click those videos and tell YouTube I'm not interested in it. That helps keep my homepage fresh while still being pretty good about recommending stuff I like.

One thing I think must be deeply challenging about recommendation on YouTube is that many videos like DIY informative stuff only warrant being watched once. But music, DJ mixes, livestreams, etc. I will watch over and over. So the signal "did I watch this" might mean "definitely do not show it again" for some videos and "definite do show it again" for others. It's probably hard for the system to distinguish those.