Well, that phone is a Xiaomi, not a Samsung (who had already made my shit list some years ago thanks to all their bloat), and the new ROM is just a bloat free MIUI, so from the same maker as the phone.
And yeah, as somebody else mentioned, if the banking app stopped working it would be the bank losing me - it wouldn't be the first time I changed banks because they pissed me off.
Retail banking as a service is a commodity - they're pretty much all the same - so sticking or not with a bank should be something one does based on cost and convenience and a banking app that doesn't work on my phone reduces convenience.
As it so happens my banking app works fine.
That said, your alert can be important for other people and points one more reason to avoid Samsung like the plague.