You need to send at least one screenshot with a 7-inch tablet and one 10-inch tablet to your store’s list on the Google Play console.
For the app to appear in the "Designed for Tablets" list on the Play Store, you must upload at least one 7-inch and one 10-inch screenshot. If you previously downloaded screenshots, be sure to move them to the desired area below.
It is not clearly written that this is due to the message “This application may not be optimized for your device. But I presented 7-inch and 10-inch screenshots, and as soon as the update appeared, the message disappeared.
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