Parents often leave small children with tablets to watch cartoons. Some are innocent but when the auto-play is left on they cycle into the incredibly creepy and disturbing content that you describe. There is one that I saw where a small baby is injected with a hypodermic needle and the baby cries at first then starts giggling. It’s grooming pure and simple. The music too is very hypnotic and I’m sure any parent listening but not watching is thinking that their baby is safe and just being amused.
There are several repeating themes. Getting shots/needles is one. Spiders and scary animals is another. I read an article on it yesterday and the scales fell from my eyes; I went from "something seems wrong here" to a total opponent of Youtube, and the content you describe.
For instance, no country on earth still gives children vaccine injections in the butt, and yet Youtube is full of that. It is pedophilic porn, pure and simple. ElsaGate is real, and Mark Zuckerberg needs to swing from a rope ASAP. He is the enemy of my civilization. He has harmed my children.