My app compiled fine, but when uploading to the App Store, I got this error":

Return status of iTunes Transporter was 1: ERROR ITMS-90208: "Invalid Bundle. The bundle Runner.app/Frameworks/App.framework does not support the minimum OS Version specified in the Info.plist."

A quick search on Google returns this post: https://github.com/flutter/flutter/issues/58200

Basically, setting the version from 8 to 9 in ios/Flutter/AppFrameworkInfo.plist's MinimumOSVersion did the trick.