After adding SplashActivity.java with above content, push notification onclick listener stopped working.

Correct content in SplashActivity should be-

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);

    Intent intent = new Intent(this, MainActivity.class);

    // NOTE: This is necessary to forward the original intent on to the main activity.
    // This makes firebase.notifications().getInitialNotification() work.
    intent.putExtras(this.getIntent());

    startActivity(intent);
    finish();
}

Reference: https://github.com/invertase/react-native-firebase/issues/1027#issuecomment-390557446