New metadata for Mac App Store product pages.
Now you can add up to three app previews, an app subtitle, and up to 10 screenshots to your product page on the Mac App Store. These details will be seen by customers running macOS 10.14 or later.
The app preview specifications are 1920 x 1080 pixels with a 16:9 aspect ratio.
To learn more about adding app previews and screenshots to your product page, visit App Store Connect Help.