So i have a small basic plan server i opened it to the public and everyone came on after about a month the griefing happened i had to rebuild spawn 4 times i swear spawn is protected but he just keeps griefing i don't know how to catch him is there a plugin i can use to find out who it is I've tried looking at players in the control panel but theres so many players in it i whitelisted the server only my cousin can play and me there has to be a way i can catch this guy is there such a plugin or way??
You can use a block logging plugin such as Prism, Core Protect, HawkEye Reloaded, etc. to lookup block changes/interactions and roll them back. What do you use to protect spawn with?
The vanilla spawn protection? Make sure your spawn size is big enough in your server.properties. If you want you can install a plugin for protection for easier use and flexibility such as WorldGuard.