From the first lawsuit, Meta knows that teenagers and young adults are a "substantial and critical market".
"Meta and their advertisers want to attract young people because they are more likely to: (1) be influenced by advertisements; (2) become lifelong customers; and (3) set trends that the rest of society emulates."
Of course that's true for every other social media site that's advertiser-supported, which is nearly all of them (and we know Bluesky will end up turning on ads at some point).