c# – Calling an API endpoint from MVC frontend; GET request with username as parameter

In my application, I only show users their own data. For that, I need to know in the backend, which user is requesting data. I use the username for that and therefore, I need to send the username as part of the GET request.

The method in question, located in MVC-controller:

public async Task<IActionResult> Index()
    ////Here, I pass username. ApiClient is a HttpClient and has a configured BaseAddress.
    var response = await ApiHelper.ApiClient.GetAsync("username?username=" + User.Identity.Name);
    var result = await response.Content.ReadAsStringAsync();
    var options = new JsonSerializerOptions { PropertyNameCaseInsensitive = true };
    List<MatchViewModel> match = JsonSerializer.Deserialize<List<MatchViewModel>>(result, options);
    return View(match);

Whatever feedback, advice or critique you might have, I am interested. Thanks in advance.