Shit Is Stupid.
Backups are stored on Google Drive in folder General/Backups.
The backup is uploaded by Service Account called backup@rfid-tracker-backups.iam.gserviceaccount.com. Credentials for it can be found in Google Cloud Console, logged in as RoboPC account, in the RFiD Tracker Backups project, in the IAM & Admin ⇒ Service Accounts ⇒ backup ⇒ Manage keys ⇒ Create new Key ⇒ JSON format.
This Shit Sucks.