Firebase storage requires twice during upload

Question

I found that storage requires twice during uploading a single file
Like this:
Uploading : 0 out of 19160
Uploading : 19160 out of 19160
Uploading : 19160 out of 19160

May I ask is it possible to request once during upload?
Because it charges by request times. I am worried abot this. Thanks.
Download just requests once, that is fine.

Best wishes

Code is similar with:

StorageReference _storageRef = FirebaseStorage.DefaultInstance.RootReference;
StorageReference _saveDataRef = _storageRef.Child("data");
string localFile = "...";

 public void UploadFromFile() 
    {
        _saveDataRef.PutFileAsync(localFile)
            .ContinueWith((Task<StorageMetadata> task) => 
            {
                if (task.IsFaulted || task.IsCanceled) 
                {
                    Debug.Log(task.Exception.ToString());
                }
                else 
                {
                    StorageMetadata metadata = task.Result;
                    string md5Hash = metadata.Md5Hash;
                    Debug.Log("Finished uploading...");
                    Debug.Log("md5 hash = " + md5Hash);
                }
            });
    }