These are being automatically generated via trending keywords &c. Here’s a pretty good explanation (that gets weirder and more disturbing with every paragraph).
https://medium.com/@jamesbridle/something-is-wrong-on-the-internet-c39c471271d2
From your excellent link, which attempts to describe in excruciating detail the technology that easily, rapidly and anonymously generates spiritually/psychologically damaging content, which gets fed into streams of benign content that children watch:
This, I think, is my point: The system is complicit in the abuse.
And right now, right here, YouTube and Google are complicit in that system. The architecture they have built to extract the maximum revenue from online video is being hacked by persons unknown to abuse children, perhaps not even deliberately, but at a massive scale. I believe they have an absolute responsibility to deal with this, just as they have a responsibility to deal with the radicalisation of (mostly) young (mostly) men via extremist videos — of any political persuasion. They have so far showed absolutely no inclination to do this, which is in itself despicable. However, a huge part of my troubled response to this issue is that I have no idea how they can respond without shutting down the service itself, and most systems which resemble it. We have built a world which operates at scale, where human oversight is simply impossible, and no manner of inhuman oversight will counter most of the examples I’ve used in this essay.