Google sign in failed com.google.android.gms.common.api.ApiException: 10:

When using App Signing by Google Play and Firebase, you need to add the SHA-1 fingerprint of the App signing certificate (found on Google Play Console/ Release Management/ App signing certificate) to the Firebase Console/ Settings/ SHA certificate fingerprints

Updated location for the SHAs: Google Play Console > Release > Setup > App integrity

Basically problem is in the SHA1 key put on console please regenerate it and put again properly same project.

1)As the answers, make sure that your actual signed Android apk has the same SHA1 fingerprint as what you specified in the console of your Firebase project's Android integration section (the page where you can download the google-services.json)

For more info, see: Generate SHA-1 for Flutter app

2)On top of that go to the Settings of your firebase project (gear icon right to the Overview at the top-left area. Then switch to Account Linking tab. On that tab link the Google Play to your project.

EDIT: Account Linking tab doesn't exist any more, instead :

1. Sign in to Firebase.
2. Click the Settings icon, then select Project settings.
3. Click the Integrations tab.
4. On the Google Play card, click Link.