I think it's creepy and bad, but "silently" is not accurate, at least in my case: Google sent each of my accounts an email telling me about it.

That's mighty generous of them. Does the mail contain an opt-out link?

	▲	dsvf 4 hours ago \| parent [-]
		In fact yes, my email did contain clear instructions: "You can manage this setting anytime on your $Phone_Model by going to Settings > Google services > All services > Phone number verification."