You should use implementation of WakefulBroadcastReceiver instead of FirebaseMessagingService

   public class NotificationsReceiver extends WakefulBroadcastReceiver {

        @Override
        public void onReceive(Context context, Intent intent) {
            //process data from intent
            abortBroadcast();
        }
   }

In your manifest

    <receiver
            android:name=".fcm.NotificationsReceiver"
            android:exported="true"
            android:permission="com.google.android.c2dm.permission.SEND">
            <intent-filter android:priority="999">
                <action android:name="com.google.android.c2dm.intent.RECEIVE" />
            </intent-filter>
    </receiver>