App icon with strange background

After trying two Apps in the iOS Simulator I've come across a change in the App Icon:

Both icons should be with black background, but they are resized to be presented inside a white background with the top right corner folded.

What am I missing?

Could you show how the icon looked like in iOS 14 ?

Here are the icons on iOS 14 (removed logos or relevant info due to NDA) They have full size black background.

This is how they look like on iOS 15 now, don't know what happened, tried to replicate it but it isn't happening any more.

App icon with strange background
 
 
Q