QQ pet icon can't be hidden, but in order not to let QQ pet die, you can prohibit pets from starting synchronously with QQ. System Settings-General-Option to automatically run QQ pets after canceling login.

To be honest, I'm a little confused. Your hidden icon is just a hidden icon, but the pet logs in normally. Or hide the icon just to keep the pet from landing. If it is the former, there is no way. If it is the latter, please refer to the above.