Flutter Google Sign in doesn’t work after release of flutter app

When testing Google Sign-in in debug mode. It works.
But after release it on Google Play, it doesn’t work.
In order to fix it. We have to add the Deployment SHA to the Firebase Authentication app.

1. In your Google Play Console, visit Setup > App signing
2. Copy SHA-1 certificate fingerprint

3. In your Firebase Console, visit Settings > Project settings
4. Click Add fingerprint
5. Past the copied fingerprint in previous step.

Recheck. It works!