Steps to Reproduce

This is how the application icons are displayed in the settings list, obviously with black gaps in the four corners. This is because the mask Apple uses is not the standard rounded corners, but continuous corner.

This is a slow motion video of the app when it is opened from the home screen. The black color in the transition animation is caused by the transparent part of the icon.

This animation takes the colors of the left, bottom and right sides of the icon and then spreads the colors in all three directions, but the current icon has rounded corners, so some of the colors are missing.

Expected results:

Expect to change to a style that fits the standard mentioned here: Human Interface Guidelines

Actual results:
The default icon for iOS does not fit Apple's HIG.