VssBasicCredential with PAT not working on Windows Service

I'm building a Windows Service project running .netcore3.1 that extracts some backlog items.
Running on VisualStudio (debug and release mode) works fine.

After deploying, and installing the service using SC CREATE I've got the message: "Microsoft.VisualStudio.Services.Common.VssUnauthorizedException: TF400813: The user 'MyDomain\MyComputer$' is not authorized to access this resource."

But I'm using the same PAT and the same URL.

Here is the code that I'm using:

var creds = new VssBasicCredential(string.Empty, "My PAT");
var collectionUrl = new Uri("The collection URL");
var connection = new VssConnection(collectionUrl, creds);
var witClient = await connection.GetClientAsync<WorkItemTrackingHttpClient>();

The exception is thrown when connection.GetClientAsync is called.

Any ideas on why it is working running on Visual Studio but not as a Windows Service?

Thanks

Start at the connection.GetClientAsync() call and compare the identity and credential context when the code runs in Visual Studio versus the installed Windows Service. Done means isolating why the PAT request is evaluated as MyDomain\MyComputer$ and documenting or implementing a verified resolution.