No end-to-end encryption
https://www.bleepingcomputer.com/news/google/google-will-add-end-to-end-encryption-to-google-authenticator/
Google is bringing end-to-end encryption to Google Authenticator cloud backups after researchers warned users against synchronizing 2FA codes with their Google accounts.
This week, Google Authenticator had finally received the long-awaited feature of being able to back up 2FA tokens to the cloud.