Issues with Firebase Push Notifications on Web and Mobile App

I am currently implementing Firebase for push notifications on both a website and a mobile app. After successful configuration, the push notifications are functioning properly on the mobile app; however, I am encountering issues with the web implementation.

Problems:

Notifications are displaying twice on the web.
Is it possible to expose the notification data publicly for users to inspect?

Here is my Firebase configuration code that i use in script:

var firebaseConfig = {
  apiKey: "API_KEY",
  authDomain: "PROJECT_ID.firebaseapp.com",
  databaseURL: "https://DATABASE_NAME.firebaseio.com",
  projectId: "PROJECT_ID",
  storageBucket: "PROJECT_ID.appspot.com",
  messagingSenderId: "SENDER_ID",
  appId: "APP_ID",
  measurementId: "G-MEASUREMENT_ID",
};

I would appreciate any guidance or suggestions on how to resolve these issues.

Thank you!

I have set up Firebase Cloud Messaging (FCM) for both my mobile app and website. After following the official Firebase documentation, I was able to successfully receive push notifications on the mobile app.