using System;

using Newtonsoft.Json;

using Newtonsoft.Json.Linq;

public class Program

{

    public static void Main()

    {

        var json = "{\"sku\": \"articlenumber\",\"lastModified\": \"2022-05-06T10:07:23.934Z\", \"quantity\": 20}";

        var settings = new JsonSerializerSettings { DateParseHandling = DateParseHandling.None };

        JObject data = JsonConvert.DeserializeObject<JObject>(json, settings);

        data.Value<string>("lastModified").Dump();

        data["lastModified"].Value<string>().Dump();

    }

}