Your Android phone has been quietly adding your number to every Google account on it

People started noticing because of the email. It comes from noreply-phone-verification@google.com, it says your number has been verified, and it lands for an account you are certain you never gave a number to. Google's own help page explains why without much ceremony: "We verify the phone number and add them to all Google Accounts that are signed in on the device." Current accounts, future accounts, and any number that turns up later.

For most people this is harmless plumbing. The number is what makes account recovery, RCS messaging, emergency location and Quick Share work. The problem is for anyone who keeps accounts apart on purpose. A second account for selling things, a volunteering address, an old one used only for signing up to newsletters, a work profile you would rather not have tied to your personal mobile. If they are all signed in on the same handset, they are now joined by the same number, and nobody was asked first.

Turning it off takes two passes. On the phone, open Settings, then Google, then All services, then Phone number verification under Privacy and security, and switch off the automatic option. That stops new links but does not undo old ones. For those, sign in to myaccount.google.com for each account in turn, go to Personal info, Contact info, Phone, and remove the number there. Glance at the Usage section while you are in there, because a number can also be sitting in two-step verification or as a recovery number, which are separate settings. Several people have reported the device toggle switching itself back on, so it is worth a second look in a week.

The same audit is worth doing on the PC. Tendvane's Privacy and accounts check shows which Windows accounts exist on the machine, which are signed in, and which have no password at all.