I sense there are two processes at work here. One is simply an algorithm that recommends more of the same. If I watch a Jordan Peterson video, I start seeing recommendations for his other lectures and podcasts. I doubt YouTube's algorithm is specifically trying to change my views politically. Likewise, if I end up seeing a lefty BreadTuber's video, I start to see more socialist videos.

The other thing is that we really don't have shared definition or word-feel for "extremism". The people who are the most vocal about curbing extremist content also happen to be wildly partisan. I don't think that is a coincidence. I sense the false-positive rate is extremely high in this regard.