Frankly, the proper solution is to ban social media regardless of age. We are already doing it with heroin and other similar substances and clearly social media are pretty bad for everyone and anyone.
We will not go for the proper solution, not because it's not the proper solution but because powerful people won't allow it.
If you do look at the things we have indeed banned, you will find that they are mostly coming from outside our countries. It's not cut and dry, but it's very geopolitical pretty often.
You can't ban the sale of tobacco either because its been proven that any attempt to soft-ban it like they have done is Australia by raising the prices enormously has simply created a black market that the government has no control over.
Finally, the war on drugs which has cost hundred of billions of dollars worldwide has completely and utterly failed. You can get drugs delivered to your door step in any major capital of the western world today. The quality is better than before and the delivery is fast and discreet.
But, whatever it takes. Social media in combination with mobile phones is destroying the latest generations. Add AI in the mix, and we're on the road to Idiocracy.