A problem occurred evaluating project ':app'.

Could not get unknown property 'flutterVersion' for extension 'flutter' of type FlutterExtension.

i got error on this code implementation "io.flutterflutter embedding release${flutter.flutterVersion}", how to fix it?

Ask a flutter community? Or at least try in #C03EM93810S. You try to use a property that does not exist. There is not much more to say from a general Gradle perspective. Besides maybe that I strongly recommend switching to Kotlin DSL. By now it is the default DSL, you immediately get type-save build scripts, actually helpful error messages if you mess up the syntax, and amazingly better IDE support if you use a good IDE like Android Studio or IntelliJ IDEA