According to this answer How to solve "Your APK's version code needs to be higher than 2." in Google Play's Developer Console? I have just changed the vers
If you get this error for your Flutter App's Android APK, in your app/build.gradle file under defaultConfig {}
comment out
versionCode flutterVersionCode.toInteger() versionName flutterVersionName
and add
versionCode 2 versionName "2"
or "previous version code" + 1.