Why are my ex's friends (F21/M21) looking at my (F20) social media constantly?

Pretty much what it says in the title. Dated a guy for over a year. He ended things because he was dealing with his own emotional baggage. I met his friend group once, they seemed pretty nice. When things ended we decided to go NC, but then i started noticing his friends were looking at my social media.

We didn't end things on bad terms and he's NOT the type to gossip or talk badly about people, so I'm not convinced he's been talking to his friends about me in a bad way or has put his friends up to this whatsoever. Just trust me on that one. But i also can't understand why his friends would care enough about me to stalk my social media when I've only interacted with them on one occasion. They don't follow me on social media so i know it's not because my posts have been coming up on their feeds.

I guess I'm just confused. If it was once or twice i would've thought nothing of it, but at this point I've noticed 4 of his friends checking out my profiles and it's been 3 months since i started noticing it. I have no idea what to think about it all.

What do you guys think?