How can I create a bot detection AI for Minecraft?

I want to program a fishing bot detection bot.

Do you mean as a plugin to get AFK farmer?

What tells me you have no idea?

Quite simply: the fact that absolutely no AI is required for this.

Simply use the PlayerMoveEvent: if the player does not move over a period of x minutes, kick.

I mean where it learns how fast you fish and how long you stand normally or whether you always throw the rod equally far, etc

And why would you have to "learn" that? It is nothing more than stopping time. AI needed? No.