Some Apps’ data and passwords don’t get transferred when you change iPhones.
Google Authenticator and Signal are among two that I found needed QR codes to transfer directly between the phones.
What are some Apps you needed to manually transfer?
Has anyone made a list or found a Wiki that would be helpful to people changing phones?
The app (google Authenticator) uses it to verify your device. You can use the saved image to authorise your new device through the app.