There are actually anti-cheat plugins you can install from the 'plugins' section of your server dashboard, like Matrix Anti-cheat or Phoenix Anti-cheat. These would definitely aid you in dealing with those pesky hackers owo
Going through the appropriate steps from this link might be of help to you
https://superleague.zendesk.com/hc/en-us/articles/360015767134-My-server-won-t-start
If you don't have it installed then it might be a problem of low server tps or just high ping in general where you sometimes get teleported backwards a few blocks.