You have to curate the recommended for you list by clicking on the options pull-down menu - the three little dots on the corner of the video you want to stop appearing in your recs - and choose "not interested" and when prompted "tell us why", select "not interested in this channel". Do this a few times and YT will stop recommending you such videos - at least until you or someone on your computer or device looks at such videos again.
I did this a while back and now I follow like 200 different communist Youtubers that got recommended to me - when the algorithm starts working for you, it really starts working for you.
YT does some very awful stuff to the point I pretty much defend the algorithm now because it's far from the worst concern. Nonces using kids' videos to share nonce porn links, for example, or YT's demonetisation strategies that constantly impoverish the users that made the service the social media hub it is now rather than the place you went to find copyright-infringing uploads. YT has many problems, but the algorithm one is at least fixable.