Hi everyone. For those who have been getting the "unauthorized" message since this morning: I had the same issue. I uninstalled the modified version and installed the official one to test it out; I recovered my account via Google linking, and it worked without triggering the error message.
You might want to try this yourselves to see if it works—it would be a shame to miss out, especially if you haven't actually been banned.
Also, don't hesitate to repeatedly tap the Google button while recovering your data if you get the "Google data transfer cancelled" message.