Found out my 13yo has a secret Instagram account

So yeah. That was fun to discover. The official one we know about has like 40 followers and bland posts. The hidden one has hundreds of followers and he's... actually kind of funny? Posting memes, commenting on stuff, has a whole persona. Part of me is annoyed he hid it, part of me is like "okay at least he's not doing anything dangerous." I haven't confronted him yet because I'm still processing. Do I pretend I don't know? Do I tell him I know? Do I just accept that he's gonna have spaces I don't know about now? This parenting thing is wild man.