Firstly, I think the best way to “solve” this exploit is to eliminate any alien code by finding the backdoor where it is sourced. There are many backdoor script locators such as this one.
I mean, if you mean this exploit specifically, you can do a while wait() do and scan for Animation objects and delete them, with a whitelist of the animations that belong to you. But I recommend taking the information above.
Another thing you can do is you can set a RemoteEvent to fire all clients, detect for that one foreign gui, and delete it. But it can be intercepted by exploiters again as they have access to everything client sided.