Developer kicks are required to have the prefixed message to differentiate it from an internal disconnection. I guarantee you that you’ve never seen an experience that has hacked the fixed message out of the kick prompt.
You could theoretically show them your own GUI and then crash them, but it wouldn’t stop exploiters because crashing them would have to be done on the client and exploiters can stop client scripts. Also idk if forcefully crashing users is necessarily allowed
It is just an idea, you can remove the character, clean PlayerGui and place a ScreenGui, it does not matter if the player removes it, he will not be able to play since he cannot reset his character, it would not work with all hackers, but yes with most, I guess