You are assuming facts that aren’t in evidence. Apple has an entire program for developers. Developers include banks that develop apps internally and companies that specialize in financial apps and cater to small and medium size institutions.
Developers have private forums similar to what we consumers have here. The difference is Apple Software engineers and support staff regularly post and assist with programming issues etc. Apple makes available extensive testing labs for the developers to test their software on many different devices and operating systems. This helps developers find bugs before their app is released to their customers.
Developers get advance copies of new iOS upgrades months in advance, so developers can make necessary updates to their own apps.
Apple does not maintain lists of apps that will work or not work. That rests solely with developers. Apple administers apps nothing like you imagine. They investigate consumer complaints and violations of terms and conditions of the App Store.
If and when an app is available to the public is almost totally under the control of the developer. A developer can wake up one morning, log into their App Store account and stop all distribution of the app in the blink of an eye. Apple is only aware after it’s done. The developer needs give no advance warning or explanation. This is all laid out in the terms and conditions.
Anyone that has developed apps for the App Store knows how it works. Your bank pulled the app. You don’t like it, but rather than voicing concerns to your bank, the one entity that can rectify your concern, you attack what you perceive to be the big bad corporate giant that somehow decided to pick on your bank. That, sir, is a fantasy.