Nobody gives a rat's ass about kids except their own. This is because of Trump. Also Russia.
This is an effective way to kick American social media companies out of your country. Like most socially destructive and unpleasant things you kind of have to get em young. If you don't hook kids early on they don't become terribly interested in social media.
What they tend to do is they tend to find a platform their friends are on and just communicate with their friends. They don't engage in the Doom scrolling that you need to manipulate political outcomes and control a population and gather shitloads of highly confidential and valuable information. Just a little IMing back and forth and that's no good if you're a Russian propagandist or a billionaire psychopath.
Facebook has had that problem for ages and they stay ahead of it by buying up every tiny little potential competitor or small Network and then forcing kids into their main platform where they can be monetized and propagandized.
Since Trump threatened to invade Greenland Europe sees America as a existential threat, which much as I hate to admit it is correct. My country literally made a pedophile president of the United States twice we can no longer be trusted.
If you're up just banned Facebook and Twitter there would be legal challenges and they would probably lose but by cutting off the kids in 5 or 10 years Facebook and Twitter will be dead in Europe.
The funny thing is I'm sure that both Facebook and Twitter know this well I mean Facebook Twitter is run by an imbecile. So I do wonder how they are going to counter this or if they even can