You may get this kind of message when you are logged in to your game account on several devices at once.

Thus we recommend that you make sure to not leave the game running in the background when you close it on one device and launch it on another one.

If you have just one device, please make sure you didn't log in to your personal account from anybody else's device, or you didn't give your personal data to somebody else who could launch your account on their device occasionally.