u/Acceptable-Cream-647

I started a Minecraft server with the Lillypad server creator, we had some issues today and while going through the user cache data, I found this. The user isn’t in a whitelist profile and is only found in user cache and username cache, does anyone know what or who this is? My friends are worried as we’ve had griefers before and don’t want anything getting messed up here, thank you for help in advance!