using System;

using System.Collections.Generic;

using System.Linq;

using System.Text.Json;

using System.Text.Json.Nodes;

using System.Text.Json.Serialization;

var json = "{\n  \"TaskLists\": [\n    {\n      \"Name\": \"List1\",\n      \"ToDoTasks\": [\n        {\n          \"Name\": \"Task1\",\n          \"Note\": \"\",\n          \"LastEdit\": \"2022-04-19T13:05:10.0415588+02:00\",\n          \"Finished\": false\n        },\n        {\n          \"Name\": \"Task2\",\n          \"Note\": \"\",\n          \"LastEdit\": \"2022-04-19T13:05:13.9269202+02:00\",\n          \"Finished\": false\n        }\n      ]\n    },\n    {\n      \"Name\": \"List2\",\n      \"ToDoTasks\": [\n        {\n          \"Name\": \"Task3\",\n          \"Note\": \"\",\n          \"LastEdit\": \"2022-04-19T13:05:18.3989081+02:00\",\n          \"Finished\": false\n        },\n        {\n          \"Name\": \"Task4\",\n          \"Note\": \"\",\n          \"LastEdit\": \"2022-04-19T13:05:23.0949034+02:00\",\n          \"Finished\": false\n        }\n      ]\n    }\n  ]\n}";

var root = JsonSerializer.Deserialize<Root>(json);

Console.WriteLine(root.TaskLists.First().ToDoTasks.First().Name);

​

public class Root

{

    public List<TaskList> TaskLists { get; set; }

}

public class TaskList

{

    public string Name { get; set; }

    public List<ToDoTask> ToDoTasks { get; set; }

}

​

public class ToDoTask

{

    public string Name { get; set; }

    public string Note { get; set; }

    public DateTime LastEdit { get; set; }

    public bool Finished { get; set; }

}