You might also choose to manually support multidex by following Android’s guides
and modifying your project’s Android directory configuration. A
multidex keep file must be specified to include:

Also, include any other classes used in app startup.
See the official Android documentation for more detailed
guidance on adding multidex support manually.

Reviewing the app manifest

Review the default App Manifest file,
AndroidManifest.xml,
located in [project]/android/app/src/main and verify that the values
are correct, especially the following:

Edit the android:label in the
application tag to reflect
the final name of the app.

Add the android.permission.INTERNET
permission if your application code needs Internet
access. The standard template does not include this tag but allows
Internet access during development to enable communication between
Flutter tools and a running app.

Reviewing the Gradle build configuration