I see, you should list that in the original post. You should do that for any other trouble shooting method. Makes it easier for the engineers.
For example: does it work only when the player joined recently or does it happen even when the player has been in the game? Maybe it could be loading related?
The “kicking UI” in studio does not show. Instead, it logs it in the output, in which it would say “Kicked from server: (message)” or something like that.
Send us a video doing it in the roblox player or roblox app (whichever you use) or such, that will help.