More important, many people don't backup the activation code or QR code so in case their device is broken, they can not self-recover 2FA............
In the case someone hasn't saved that code, it's still possible to backup the 2FA codes.
Google authenticator allows you to export your accounts using a QR code. (more than 1 QR code, if you have many accounts)
You can save that QR code and use it whenever you want to use a new device for any reason.
To do so, you should tap on the "3 dots" button at top of the screen, select transfer accounts and then "Export accounts".
Since your phone doesn't allow you to take a screenshot from the QR code due to security reasons, you have to take a photo using another device.