Ask HN: How to get rid of anti-scientific ads / YouTube content

After watching several documentaries about the impact of Man on our environment from reputable sources, e.g BBC, Arte etc. on YT I am now getting bombarded by anti-scientific ads / conspiracy theory nutcase content. This was on newly setup machine on Firefox, no YT / Google account. Why on earth is Google pushing this crap to my recommendations?

So my actual question is, how to get rid of this crap? This is worse than any crap 8chan was disseminating. How to make Google and Co. stop giving those people a platform?