There's a button, "not interested". Click it. My youtube is mostly pretty nice. I get recommendations for cooking videos because I subscribe to and watch a couple of channels. I get recommendations for GDC videos, various programming videos. I mark videos as not interest often. And if there is something It think might give it the wrong idea I often right click and view in an incognito window. Have had very few issues keeping my youtube recommendations relatively clean, and I really enjoy some channels. Souped Up Recipes, Chinese Cooking Demystified, Coding Adventure, Veritasium, Kurzgesagt