I had this same problem. I fixed it by doing this: https://stackoverflow.com/a/66609391/8948894
Basically, in the appstore connect go to your app then under the Pricing and Availability tab, I unchecked the Make this app available for Apple Silicon Mac Availability, and now my iPhone screenshots show first and it removes the "Designed for iPad". It took a couple hours to update on the store though.
Topic:
App Store Distribution & Marketing
SubTopic:
General
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