Ask HN: Received unrequested Google verification code e-mail, but have SMS 2FA?

I have SMS 2FA enabled on my Google account. A few minutes ago, I received a couple of consecutive e-mails from Google (seems legit, not spoofed), with a verification code.

Obviously this is alarming and I will be changing my password. The account activity logs don't show any unauthorized devices. However, I'm wondering why I would get this in e-mail form at all when I have SMS 2FA enabled (and all legit requests have been received through SMS)?