I don't think there's an online backup it does have an export option but you can only export them if you are going to move the authenticator to a new device because it would generate a QR code that you need to scan to another device. I never tried exporting  my authenticator with email I saw this as another option but you can just ignore it and use the QR code option instead if you want to export and move it to a new device.

However, saving the secret code to offline device still the best way to backup your authenticator for future recovery.