Attached is the reference from the firebase

I am saving data as here
enter image description here

    const productRef = await addDoc(collection(db, `rating_book/${product.bk_ID}/ratings`), {
      bookId: product.bk_ID,
      date: Timestamp.now(),
      rating: rating,
      token: JSON.parse(localStorage.getItem('user')!).token,
      username: JSON.parse(localStorage.getItem('user')!).username
    });

This is another snapshot for complete picture from firebase.
enter image description here

I am trying to fetch data but i am not getting data here. why?

  const fetchTopRatedBookIds = async() => {
    try {
      const ratingsSnapshot = await getDocs(collection(db, 'rating_book'));
      const bookRatings: { [bookId: string]: number[] } = {};
  
      await Promise.all(ratingsSnapshot.docs.map(async (doc) => {
        const ratings = doc.data().ratings as number[];
        bookRatings[doc.id] = ratings;
        console.log(`Book ID: ${doc.id}, Ratings: ${ratings}`);
      }));
  
      const averageRatings = Object.entries(bookRatings).map(([bookId, ratings]) => ({
        bookId,
        averageRating: ratings.reduce((acc, curr) => acc + curr, 0) / ratings.length,
      }));
  
      console.log('Average Ratings:', averageRatings);
  
      const sortedBooks = averageRatings.sort((a, b) => b.averageRating - a.averageRating).slice(0, 3).map(entry => entry.bookId);
      console.log('Sorted Books:', sortedBooks);
  
      return sortedBooks;
    } catch (error) {
      console.error('Error fetching details', error);
      return [];
    }
  };

Any suggestions is appreciated.