Eh
What about needing a new one each day?
Like the point of the pet is that it’s supposed to be difficult to communicate with. If someone can make their own cipher, everyone understands how it works, and they can continue using it for the rest of the game, then they’re not really a pet anymore, since again the point of the pet is to have difficulty communicating the entire game.
Do you feel me? And if so, do you have any better ideas on how to fix this problem than what I proposed originally? The reason why I want to ban existent ciphers is that someone could just look them up and have the key instantly. Like probs if u googled what was there it would tell you what it was.