Sometimes, very rarely, devices playing on a Multiplayer game (Pocketmine or LAN multiplayer) will send chats in raw JSON. It happens to pretty much everybody, and has been happening for a while. I run a Plug Pocketmine server, I also run a LAN server, and it happens every once in a while. I also see it when playing on regular Pocketmine servers. People try to type regular chat and the Raw JSON text which is the code for the chat will pop out. It happens to both the host of the server, and the clients. I use an Android Samsung Galaxy S7.