I don’t know about time limits, but social media does get censored on a per-country basis depending on the government of each country. Also, each person has their own tailored content based on the algorithm that it might as well be considered a different version.

We could just as easily mandate restrictions on data or require timers for children on social media instead of doing a full ban. Note that the US was fine with keeping tiktok if they sold to an American company. Something tells me the brain rot would not be lessened and no special timer would be implemented by the new ownership if it were to have gone through.