My personal opinion is that it’s one of the first large cases of misalignment in ML models. I’m 90% certain that Google and other platforms have been for years already using ML models design for user history and data they have about him as an input, and what videos should they offer to him as an ouput, with the goal to maximize the time he spends watching videos (or on Facebook, etc).
And the models eventually found out that if you radicalize someone, isolate them into a conspiracy that will make him an outsider or a nutjob, and then provide a safe space and an echo-chamber on the platform, be it both facebook or youtube, the will eventually start spending most of the time there.
I think this subject was touched-upon in the Social Dillema movie, but given what is happening in the world and how it seems that the conspiracies and desinformations are getting more and more common and people more radicalized, I’m almost certain that the algorithms are to blame.