How to resolve "Deserialization of Untrusted Data" error reported by Checkmarx scan issue

Question

I have integrated Checkmarx scan tool with Azure DevOps pipeline. I am getting high risk results after running the ASP.Net Core Web API related pipeline. I have tried multiple approaches and run the pipeline. Still now there is no luck. Could you please help me to resolve the issue?

C# Code:

Uri requestUri = new Uri("https://webapi.com/token");
HttpContent httpContent = new StringContent(System.Text.Json.JsonSerializer.Serialize(new { access_token = accessToken }), Encoding.UTF8, "application/json");
var result = await client.PostAsync(requestUri, httpContent);
if (result != null && result.IsSuccessStatusCode)
{
  var content = await result.Content.ReadAsStreamAsync();
  var authResponse = await System.Text.Json.JsonSerializer.DeserializeAsync<TokenResponse>(content);
  var authToken = authResponse.AuthenticationToken;
}

TokenResponse.cs:

class TokenResponse
{
  public string AuthenticationToken { get; set; }
}

Error Message:

The serialized object PostAsync processed in async in the file at line 42 is deserialized by DeserializeAsync in the file at line 46.