So I have noticed there has been a lot of alters on the server and there is a quick fix for this, add an anti-bot filter there is many free ones but also a lot of good payed ones. (
https://www.spigotmc.org/resources/2ls-antibot-the-ultimate-antibot-plugin.62847/ )
Why I suggest this is because I am staff on a different server who has this, makes it way harder for people to ban evade and also people wont be able to alt every two minutes. It will also make the server more fun and keep alters and bots away from the server.