My 16 M cousin is chatting with a 24 F 😬💀

I don’t really know where else to post this, but it’s about My cousin (16) is kinda like a brother to me. We were at a function, super bored, so me, him, and my sister found a spot to chill.

At some point, he was glued to his phone, so I asked what he was doing. He said “nothing,” but then told me he’s been chatting with a girl… who is 24. He’s been talking to her for a few days.

I didn’t snoop or anything, but honestly, the age gap freaks me out, feels off to me 😭 I don’t want to overstep, but I’m worried.

What should I do?