When running flutter build ipa --export-options-plist ... the log output is always "Building App Store IPA..." because the message only takes into account the --export-method arg (and falls back to appstore if not set), and ignores what's set as method inside the plist.
Rather cosmetic issue, but it does lead to confusion - at least I checked the code to see if the .ipa is built with the method set in the plist. (It is, it's just the message that is wrong.)