Wow! That provides some great info on this. Still leaves me wondering if the end result wasn't by design though. It's kind of hard to buy into the "Opps" explanation.
It certainly could've been done by design but I think more likely this was a doomed project from the start. They rushed this app out with too little time for testing.
I don't want to speculate too much on that screenshot but it looks like they have an error in their Auth0 integration. When you use a service like Auth0 you give it a redirect url to send authenticated users to. It looks like they passed in an invalid url for that redirect. Maybe they only tested this 2fa step locally and something was different when they deployed to users' phones, I can't say for sure, but it doesn't look good.
In particular it looks like Firefox Fenix/Preview (or possibly Reference Browser), not Fennec (regular Android). Only Fenix and Reference have bottom URL/tab bars. Fenix has a purple "Try Again" button, I don't know about Reference Browser, and Fennec has a gray button.
One possible issue is that Fennec/Fenix doesn't open http URLs in external apps by default (unsure about custom protocols), whereas Chrome does.
My favorite screenshot is the last one, it looks like a generic mobile Firefox error for a misspecified URL.