using System;

using System.Text.Json.Nodes;

public class Program

{

    public static void Main()

    {

        var json = @"{

             ""props"":{

                    ""pageProps"": {

                        ""dehydratedReduxStateKey"": {

                            ""studyModesCommon"": {

                                ""studiableData"": {

                                    ""studiableItems"": [

                                        {""item1"": ""data1""},

                                        {""item2"": ""data2""},

                                        {""item3"": ""data3""}

                                    ]

                                }

                            }

                        }

                    }

                }

            }";

        var jsonNode = JsonNode.Parse(json);

        var studiableItems = jsonNode["props"]["pageProps"]["dehydratedReduxStateKey"]["studyModesCommon"]["studiableData"]["studiableItems"];

        Console.WriteLine(studiableItems.ToJsonString());

    }

}