you need to sign your apk or android app bundle in release mode flutter code example

Example: flutter You uploaded an APK or Android App Bundle that was signed in debug mode

buildTypes {
        release {
            // TODO: Add your own signing config for the release build.
            // Signing with the debug keys for now, so `flutter run --release` works.
            signingConfig signingConfigs.release
        }
    }
    // FLUTTER CLEAN AFTER THE EDIT