ASP.NET Core System.Text.Json JsonValueKind

If you want to get the object value in result,here is a working demo like below:

public void Test()
{
    //the data here is the same as reader.ReadToEnd() in your project
    var data = GetRequest();

    //your result
    var responseData = JsonSerializer.Deserialize<Dictionary<string, dynamic>>(data);
    
    //change like below
    var d = JsonDocument.Parse(data);  //JsonDocument.Parse(reader.ReadToEnd())
    var result = d.RootElement.EnumerateObject();
    foreach (var r in result)
    {
        if (r.Value.ValueKind == JsonValueKind.String)
        {
            var stringValue = r.Value.GetString();
        }
        if (r.Value.ValueKind == JsonValueKind.Object)
        {
            var m = JsonSerializer.Deserialize<TestModel>(r.Value.GetRawText());
            var Code = m.code;
            var des = m.description;
        }
    }
       
}

Model:

public class TestModel
{
    public string code { get; set; }
    public string description { get; set; }
}

Result:

The simple way is to create a ViewModel for the result like below:

public class ViewModel
{
    public TestModel result { get; set; }
    public string buildNumber { get; set; }
}

Deserialize the json string and get value like below:

var responseData = JsonSerializer.Deserialize<ViewModel>(reader.ReadToEnd());
var code = responseData.result.code;
var des = responseData.result.description;