What a shitty banking app. The malware explanation could just be customer service boilerplate. They might have just implemented some commercial fingerprinting/analysis/security library in the app that freaked out at the minimal fingerprint of the GrapheneOS profile and defaulted to locking you out.

As individuals, we need to continue defending and advocating for our privacy - using privacy-respecting phones and software even if it's difficult and organize against surveillance capitalism, or at least donate to existing advocacy groups. And the developers that make privacy-respecting alternatives more accessible. Not much of an easy way out since we're up against Big Tech on a profoundly uneven playing field.

But for immediate issues like this, I would get a cheap separate phone with regular Android to handle the app if the bank doesn't offer the same services through a browser. Try to keep it on an isolated network and only power it on when necessary.

I stopped using banking apps altogether in favor of using the website instead.

My previous bank would not allow me to do everything from the website that I could do from the app which is why they are now my previous bank and not my current bank, LOL.

I'm not telling them what my real setup is because they won't understand.

They would then tell you that only Android is supported.

Btw, i use App Manager and TrackerControl to analyze apps.

I've managed to avoid banking apps altogether but I know they often want you to be running stock Android, no rooting or whatever. There is a retail app that I sometimes use but I relegate it to a burner phone. If I had to run a banking app with any regularity, I'd probably do the same thing.