app.config.ts :

const firebaseConfig = {
  apiKey: "",
  authDomain: "",
  databaseURL: "",
  projectId: "",
  storageBucket: "",
  messagingSenderId: "",
  appId: "",
  measurementId: ""
};




export const appConfig: ApplicationConfig = {
  providers: [
    provideRouter(routeConfig, withComponentInputBinding()),
    provideFirebaseApp(() => initializeApp(firebaseConfig)),
    provideAuth(() => getAuth()),
    provideFirestore(() => getFirestore()),
  ],
};

DataSharingService.ts :

@Injectable()
export class DataSharingService {
    public isUserLoggedIn: BehaviorSubject<boolean> = new BehaviorSubject<boolean>(false);
}

I already posted 2 problems here ( sign up and login are not working after form submission ) , so I said maybe cuz firebase isn’t correctly linked to my angular project
( btw those fields in app.config.ts are not empty , just for security reasons )