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.

In another comment someone said that YTKids has an option to disable related videos, that could be a good start.

Yup. Get video apps from actual companies that have at least a semblance of QC.

PBS kids, Disney Jr, Nick Jr.