It's deliberate
I don't retain cookies between sessions, so if I visit YouTube, it's as a virgin user. And the "recommended for you" videos often include right-wing propaganda. There was even a period when Stephen Yaxley-Dickhead's "Tommy Robinson" entire channel of racist bullshit was recommended. Then there was one of medical expert Doctor Jacob Rees-Muppet "being clever" that came up all the time.
Obviously, Youtube promotes paid content. And obviously, the far-right movements pay to get people onto the radicalizing escalator.