I am going to be a bit technical, iOS engineers will know what I’m talking about!
There is no doubt that the iOS app is audited and tested for security purposes.
I just wanted to suggest something I can see visually which is a common practice among banking/financial applications.
That is when you move the app in the background. After moving the app in the background, the system takes a snapshot of the interface and that is what you see when scrolling through apps in the app switcher. That screenshot must not contain sensitive data.
I know that card numbers and funding accounts are masked with asterisks, still the account balance and portfolio are sensitive.
It is an easy fix, blurring the view or putting an entirely custom one on top.