I would legit pay money for Google to pull that piece of junk from the Play Store, because it's damn malpractice at this point, given there are so many other options that don't straight-up swallow the TOTP keys
You can back the secrets up to a text file, print them out, etc. too. They're short Base32 strings and TOTP is a standardized protocol with an RFC (6238) and everything.
Except it is cumbersome to doo on Google Authenticator. You must press export to get shown a giant QR code. You can't screenshot it. Must photo with different phone and print on a piece of paper for offline storage.