Turn off app backup

Hi Luckycrab, thanks for your question.

To my knowledge, it's not possible to exclude certain apps from the Google backup service without disabling the backup service entirely.

One thing that I think is important to note here is that a Secret Key does not just sit in Google Drive plain to see. On contemporary devices with Google's Android backup, the Secret Key in this example would be encrypted using a locally generated encryption key before it is backed up to Google's servers. That key is then encrypted with your Google account password and transmitted to Google to be stored in their Titan modules.