Players Getting Kicked When They Joined My World When I Didn't Kick Them! PLS HELP :(

So me and my friend started playing on a world when some unwanted players joined. I kicked them, and I didn't /kick @a. So then, after a while we stopped playing, and then started again. And my friend joined the game. And it said he was kicked! I invited him, (I was on Windows 10 and he was on Android.) So pls help!

EDIT: I found out that it is everyone who joins my world gets kicked. And it only happens with that world.