Anything that you don't want affecting your recommendations should be opened in an incognito/private window. Or you can just remove it from your watch history. Anything in your feed that you don't want there hit the three dots and pick either "not interested" or "don't recommend channel". Every now and then I get some dogshit recommendations but it's mostly cool music, weird tech shit, and various outdoor activity-related things now. Another option is to only look at your subscribed feed and ditch the algorithm altogether.
Oh also install the Hbomb youtube censorship addon if you don't have it. I never see fash channels thanks to it.