It's actually quite funny: they could possibly implement an algorithm that's going to move to more boring (not in child's interest) suggestions after some time

It's actually quite funny: they could possibly implement an algorithm that's going to move to more boring (not in child's interest) suggestions after some time (eg 1h of screen time) to encourage healthier viewing habits. But I think that's a harder problem to solve since all creators are going for addictive content, so figuring out interest is most important.