Are there UI rules and guidelines that developers should follow when developing apps to be published on the Apple Store?

Hello.

Recently, I stumbled across an app on the App Store called "Rhythm Trainer." It looks awesome and has great exercises for rhythm training, but the behavior of the UI drives me crazy. Let me show you one example.

In the iOS interface, the button with the left-directed arrow in the top left corner takes users back to the previous screen, which is reasonable and intuitive.

But in the Rhythm Trainer app the same button works differently.

In the screenshots above, there are three "go back" buttons, but each instance functions differently:

1. The first one takes users back to the previous screen.
2. The second one takes users to the home screen.
3. The third one takes users to the next screen.

That's confusing and counterintuitive. I believe a good UI shouldn't behave in that manner. There are also other issues with the "Rhythm Trainer" UI. I've just described one of many examples.

So I wonder if there are UI guidelines provided by Apple to encourage developers to create good, understandable UIs, unlike the example above.

Also, can I report the issue mentioned above to Apple to encourage the developers to fix it?

I would greatly appreciate any advice.