App Icon without Alpha?

Targets iOS
1

Trying to set up a TestFlight path for an iOS app. I used Apple’s Icon Composer to create (most of) the App icon files and have it in the right design. When I try to upload, I get an error

App Store Connect expects an app icon of 1024 x 1024 with no alpha channel (App Icon).

How that? Apple uses rounded corners and will create such an icon (with transparent background) by default with Icon Composer. A full background color icon would look quite ugly. Or do I misunderstand something?

2

Seems right, the system masks and rounds the corners of the Icon automatically. Looks like since Big Sur.

3

Ok, thank you! I thought Icon Composer would be the right tool …

4

It should be.