Sometimes we don’t realize and then don’t remember whom we’ve given access to our Google account in order to set up an account from another vendor.
It’s always a good idea to go to https://myaccount.google.com/permissions while you’re logged in to your Google account and review who has access to your private information.
If you use an Android based phone be careful not to remove access to important apps and make sure you do for the questionable ones. Not sure about an app? Google it and see.