This is a good reminder that your phone may not be as secure as you think. In many countries governments are able to get access or ask for this type of change t

This is a good reminder that your phone may not be as secure as you think. In many countries governments are able to get access or ask for this type of change to be made from the national telco's. The reactions you can take at the moment are to use a mobile App, (or preferably a security key!) rather than SMS backup, and if You're feeling especially uncharitable to your phone company, change the backup number google makes you enter to a google voice number rather than that of your actual phone - creating a circular situation where it can't really be used as a method for account recovery / hijacking.