Exception "The URI prefix is not recognized" from WebClient.DownloadDataAsync

I was trying to save an image from an URL and I have an inner exception inside an inner exception tellin the URi prefix is not recognized.

Full exception:

[ERROR] FATAL UNHANDLED EXCEPTION: System.Reflection.TargetInvocationException: 
An exception occurred during the operation, making the result invalid. 
Check InnerException for exception details. ---> 
    System.Net.WebException: An exception occurred during a WebClient request. --->
         System.NotSupportedException: The URI prefix is not recognized.

Some code:

imagen_tap.Tapped += async (s, e) =>
{
   Console.WriteLine("URL IMAGE BRO::::::::: " + imagen.Source.ToString());
   await api.DownloadImage(new Uri(imagen.Source.ToString()));
   string path = Preferences.Get("filePath", "");
   await Launcher.OpenAsync(new OpenFileRequest { File = new ReadOnlyFile(path) });
};


public async Task DownloadImage(Uri URL)
        {
            WebClient webClient = new WebClient();

            string folderPath = Path.Combine(Environment.GetFolderPath(Environment.SpecialFolder.Personal), "Images", "temp");
            string fileName = URL.ToString().Split('/').Last();
            string filePath = Path.Combine(folderPath, fileName);

            webClient.DownloadDataCompleted += (s, e) =>
            {
                Directory.CreateDirectory(folderPath);

                File.WriteAllBytes(filePath, e.Result); //Broken?
            };

            webClient.DownloadDataAsync(URL);

            Preferences.Set("filePath", filePath);
        }

EDIT: (forgot to add this) (NOT REAL URL) The URL is https://api.com/imagenes/partes/18005/2021062311191329243400.jpg

EDIT: (answering Jason, making sure if URL is correct on webClient)

Screenshot URI on webClient

Screenshot Opening localstorage

Screenshot Broken Line

Screenshot e in debug

EDIT:

Well... I fixed the Uri prefix...

I changed 2 things: In the Download Image I changed it from Task to string and returning a string. Code:

public string DownloadImageString(string URL)
        {
            WebClient webClient = new WebClient();

            string folderPath = Path.Combine(Environment.GetFolderPath(Environment.SpecialFolder.Personal), "Images", "temp");
            string fileName = URL.ToString().Split('/').Last();
            string filePath = Path.Combine(folderPath, fileName);

            webClient.DownloadDataCompleted += (s, e) =>
            {
                Directory.CreateDirectory(folderPath);

                File.WriteAllBytes(filePath, e.Result);
            };

            webClient.DownloadDataAsync(new Uri(URL));

            return filePath;
        }

And then I changed the way I was sending the URL.

Instead of sending a new Uri(url) I'm sending a string. That string is mounted manually again, not by taking imagen.Source (this was the real fix) Code:

Image imagen = new Image
                {
                    Source = url + Foto.ID_Parte + "/" + Foto.Archivo
                };
                var imagen_tap = new TapGestureRecognizer();
                imagen_tap.Tapped += async (s, e) =>
                {
                    string path = api.DownloadImageString(url + Foto.ID_Parte + "/" + Foto.Archivo);
                    await Launcher.OpenAsync(new OpenFileRequest { File = new ReadOnlyFile(path) });
                };
                
                imagen.GestureRecognizers.Add(imagen_tap);

So, the fix works, I was testing in the phone now and it works correctly, the fix is in the last edit.