You realize that this comment section is in response to a story where YouTube is suspending educational content, right? Someone else already mentioned Elsagate

You realize that this comment section is in response to a story where YouTube is suspending educational content, right? Someone else already mentioned Elsagate which is still an ongoing problem as noted by the GP. YouTube is not interested in providing healthy material, which is not surprising since they are owned by the world's largest advertising company. I would advocate that parents should look for better alternatives altogether rather than use it as source of education or entertainment, even with supervision. It's simply the wrong place to go for that sort of thing.