I think that facebook has been using facial recognition on every photo uploaded to their platform for a very very long time and that they already use that data in part to determine the age of users. Facebook hasn't been kicking anyone off the internet because of that data so far. Instead facebook just targeted the users they decided were children as children.
Forcing the users to verify their age changes nothing. It gives the illusion of "doing something" but it just gives facebook data they already had. What's still needed is regulating social media platforms themselves to place explicit limits on what they can do to hurt their users, including children.