[throwaway5752]

It's a fair point. Not a perfect study and they do not claim a causal relationship. However, also from the results:

Researchers found by age 5, children who spent two hours or more per day, looking at screens, were 7.7 times more likely to meet criteria for a diagnosis of attention deficit hyperactivity disorder, or ADHD, than children who watched screens for 30 minutes or less each day.

It's a substantial result. They talk about practical and ethical reasons they can't establish the causal relationship, too.

I'm guilty of being a little tongue in cheek, but I'd try to limit a kid's exposure to early screen time and ease them into things like TikTok.