App screen often not hidden in app switcher

### Steps to reproduce

On an iPhone, while element-ios is running, swipe up into the app switcher: the app screen is often not hidden (black with the green element symbol). After you further interact with the app switcher (e.g. closing a different app) the element-ios window changes into the proper hidden state.

This bug has been present for many months across all versions.

### Outcome

App screen should be always hidden in the app switcher.

This is a potential security/privacy issue, too.

### Your phone model

iPhone 13 pro max

### Operating system version

iOS 15.7 and previous versions

### Application version

current + all recent versions

### Homeserver

matrix.org

### Will you send logs?

No