Ugh, I had a similar thing happen in a game last year—someone kept joining my lobbies with a username that referenced an inside joke only a few friends knew. It freaked me out thinking it might be someone IRL messing with me. I ended up using a reverse username lookup reverse username lookup to check if the name was tied to any socials or accounts. It actually helped me figure out it was just some random troll who reused handles. Huge relief, but yeah—worth checking so you can know for sure.