Tying someone's identity to their phone number is not the answer, though.
I have this at the moment - I'm travelling, moving country every few weeks, so I need a new SIM card and phone number every few weeks. My phone number is temporary at best.
I'd massively prefer to take the risk of my identity being stolen than constantly fighting security measures that assume people never change their phone number (or country of residence, etc).
You don't need to use a phone number for google. I don't have a phone number attached to my google account at all due to the risk of sim swapping despite asking my carrier to lock it, instead i have multiple hardware keys and devices + backup codes in a safe deposit box.
If Google ever thinks you're doing something suspicious, they'll just make you authenticate using a physical device instead, by way of Android functionality they never told you about or asked you about using. Hopefully they won't demand you authenticate on a device that's defunct.
luckily, so far, this doesn't involve the phone number. Google seems to know what my device is and how to reach it without needing to know the number. Little bit scary, but really useful.
You do for lots of other things (and many people have it for Google as well). Most banking or payment, a random selection of apps that decide you now need verification, new apps in the new country...
I have this at the moment - I'm travelling, moving country every few weeks, so I need a new SIM card and phone number every few weeks. My phone number is temporary at best.
I'd massively prefer to take the risk of my identity being stolen than constantly fighting security measures that assume people never change their phone number (or country of residence, etc).