collection.orderBy() method problem whith streambuilder

[burakcbdn]

I'am trying to create something like feed with Flutter and Firebase and I want to order posts by their 'postedAt' value but the problem is when I use collection.orderBy() it is not working properly. It adds new post to the random place at the feed and gives it a imageURL of random existing post (or I think it just duplicates one item in the feed). I created indexes at Firebase I tried both index types none working. The strange thing is, when I'm adding new post from the phone when my adding completed it just works fine but when listing on the other phone it shows described behaviour.
when I hot reload it works correct (last added post shows up on the top) but then it continues the bug.

I created indexes at the firebase.
Note: I used likes property just because it wants two fields
indexes:

Example document:

Note: postedAt is an integer.

here is the code:

StreamBuilder(
    stream: FirebaseFirestore.instance
      .collection("users")
      .doc(FirebaseAuth.instance.currentUser.uid)
      .collection("posts")
      .orderBy('postedAt', descending:true)
      .snapshots(),
    builder: (BuildContext context,AsyncSnapshot<QuerySnapshot> snapshot) {
       if (!snapshot.hasData) {
          return Center(
              child: CircularProgressIndicator(),
              );
        }

        if (snapshot.hasError) {
             print("error:" + snapshot.error.toString());
         }



     List<Post> posts = [];

     posts = snapshot.data.docs.map((postDoc) {
          return Post.fromDoc(postDoc);
      }).toList();

     if (posts.isEmpty) {
         return Center(
            child: Text("No posts"),
          );
     }

     return ListView.builder(
          cacheExtent: 4000,
          itemCount: posts.length,
          itemBuilder: (BuildContext context, int index) {
            return PostWidget(
                post: posts[index],
                );
            },
          );
        },
     )

[burakcbdn]

Fixed by adding key to the PostWidget()