d9780
Generally speaking if the app is working then it's better to talk to them about why it's behaving strangely. They should have a better idea of how it works.
However, it's possible they do some OS/phone checks after login (which wouldn't make sense, but programmers aren't always great at UX). It's possible they do a ctsProfileMatch check, a Google certification thing that some banks care about. Maybe take a look at this section of the website for more info: https://grapheneos.org/usage#banking-apps.