Prevent google backup of contacts? I have Google backup turned off permanently, however my contacts are still backed-up somewhere to Google cloud. I discovered that yesterday from another device that offered me to recover my contacts from a current backup.

I'm perplexed because when I open Google Drive app, it says that my device is not backed-up.

Questions:  


Where are the contacts backed up? On G-Drive, or elsewhere in my G-Account?
What more can I do to prevent Google from downloading my data to its cloud?


Details:
I have LG G6 (LG-H870, Android 8.0.0). In the Settings I have set:


Backup > Google Backup > Backup to Google Drive: Off
Users &amp; Accounts > Auto-sync account: On, otherwise my (non-Google) e-mail is not synchronized, but:
Users &amp; Accounts > my-google-account > Sync: all four sync switches are Off


In the Drive application:


Left menu > Backups: "Your device is not backed up"


My other phone is Xiaomi Redmi 4. Here:


Settings > Google > Restore contacts> Device backup list: It offers me to restore my contacts from LG-H870 created today. When I proceed, all my contacts are really restored.


The Google documentation for contacts backup,
https://support.google.com/contacts/answer/7199294?hl=en
instructs how to turn-off contacts backup.

The description of Settings > Backup > Google Backup > Backup to Google Drive says that:


  "Backup includes: Apps and app data, call history, contacts, device settings"


Edit: I've verified that my contacts are not in Google Contacts for my account.
As said already, backup of contacts by Google does not respect the general Settings&gt;General&gt;Backup&gt;Google_backup&gt;Backup_to_Google_Drive = off. This problem may occur only on LG G6, or in Android Oreo in general. 

However, I succeeded to prevent the contact backup by disabling Google synchronization services in Settings&gt;Apps&gt;Show_System&gt;choose_app&gt;disable:


Google Contacts Sync 
Google Calendar Sync 
Google Backup Transport


Now I hope that they won't get enabled again upon a firmware update.

Edit: Evidently, Google has more problems with collecting personal data than just contacts, see for instance location-tracking.