Did you watch the video where a series of marvel heroes were captured and buried up to their necks in sand? These videos are nightmare fuel for children.
Yes. Block it. Turn it off. Try handing them crayons and paper. YTKids is a product begging for your time and attention and that of your kids. It sucks and beyond that may be damaging so stop buying it (with your kid’s attention). Turn it off.
Never let your kids browse the open internet without supervision. Create curated playlists that they can watch when you aren't able to devote 100% of your time to their supervision but still want to occupy their time with videos
Block. If not, then filter the content though I can tell you their content blocking algo is terrible at blocking new content so you end up in a game of cat & mouse.
I think the author's implication is the 'wrongness' is the development of an ecosystem which encourages the creation of sadistic content marketed to children.
I agree that screen/device time is generally bad, but this goes whether it happens to be YTKids, Netflix or games.
What specifically is "wrong with the internet"? I still don't see the issue here.