In recent weeks, Google has been automatically connecting Android users' phone numbers to every Google account they are signed into on their devices—without requesting consent to do so. This means that if you are logged into personal, work, and disposable accounts on your Android phone, Google may have silently verified and linked your number with all of them even if you've deliberately kept them separate. If you that's not something you want, there's a way to fix it.
Google is automatically verifying Android users' phone numbers
As Android Authority reports, some Android users have recently received confirmation emails from an official Google address stating that their phone number has been verified. Google has required occasional phone number re-verification but appears to have updated its support documentation about a year ago to make this feature opt-out by default. As part of this process, Google also adds your phone number to all Google Accounts that are signed in on the device, including current accounts and phone numbers and any that are added or updated in the future.
You can change your phone number verification settings on Android
Disable automatic phone number verification
If you have an Android device, you can disable automatic phone number verification, which should prevent Google from linking sign-in accounts together. You can find this toggle in your Settings app under Google or Google services and preferences > All Services > Privacy & Security > Phone number verification. (Note that the exact path may differ by device.) You should periodically check to ensure this toggle remains off.
Delete associated numbers from accounts already linked
Updating this setting does not disconnect phone numbers and Google accounts that have already been linked. You can find out which are which via your Google Account Personal Info page. Select your profile picture in the upper-right corner to go through each signed-in account and open the Phone section to select and delete any numbers you don't want associated.
Review your Security & sign-in settings
Finally, Malwarebytes advises scrolling down to the Usage section on the Phone page to view which services are listed as well as reviewing your Security & sign-in settings. If you added your phone number for two-step verification or to a separate app like Google Pay, deleting it from the Phone page won't remove it entirely from your account, and you'll need to update those settings separately. Automatic phone verification shouldn't be the culprit here, but it's useful to audit what your number is being used for and on which accounts if you want to keep things separate.