When you say “moved to mobile authentication app” - as I understand it, it’s more like they added the option for using a mobile authentication app. For example - I have the 5C NFC - I can either plug it into a USB-C port (no app needed), or I can hold it at the top of my iPhone (and use NFC - no app), or I can use the app if I’m on a computer/phone that doesn’t have either a USB-C Port or NFC or doesn’t support physical keys. (Though the app has to be set up separately - just setting up the physical key doesn’t allow you to use the app.)