> kids pretending to be adults so they sneak through these filters

The real question is: how hard does it make it for them to pretend to be adults? We just need it to be hard enough that most kids won't do it.

> platforms winding back their (meagre) child safety efforts since "children are banned anyway"

If the law forces the platforms to properly ban children, I don't see how they can do that. If you're thinking that the platforms will just say "it's illegal for children to join, so we don't have to do anything because they shouldn't come in the first place", then I don't think the law is made like this.

> everyone being forced to prove their age via e.g. uploading ID (which will inevitably get leaked)

Some countries have been working on privacy-preserving age verification. I find it's a lot better than uploading an ID.

> We just need it to be hard enough that most kids won't do it.

Silly though that sounds, it might work. Because it's social pressure from other kids to be online that drives many kids into being constantly on Instagram and Snapchat. If you're not online, you don't know what's going on. The big social networks monetize FOMO.

If a sizable fraction of kids aren't on social media, that's not where it's happening any more. The pressure goes away. Or goes elsewhere.