Backup codes are automatically provisioned in the background, but they’re not shared with guests by default.
If there’s ever an issue, like a lock malfunction or connectivity problem, you can manually request a backup code for that specific reservation and it will automatically show in the guest’s guidebook.
When a backup code is used, it will automatically get rotated at the end of the reservation.
If the backup code also fails, then the guest may need your intervention to access the property.