Issue Minecraft PvP Protection?

I have a server and have the problem that as soon as a player spawns again, it has some Protection Hat and can't be attacked for the first few seconds, nor can it attack. So I want to make that Spawn busting is possible.

Does anyone know where I can show that this protection exists?

Good idea to keep players directly from your server.

Look in the server.properties after the spawn protection.

Besides, it's already in the file