using System;

using System.IO.Compression;                

using System.IO;

public class Program

{

    public static void Main()

    {

        var base64 = @"H4sIAAAAAAAA/61Ry07DMBD8F59zcGw3cXurUiQkCEIFhDi69SpUEKeKw6Gq+Hd2HSelzYVKONZ6ZryPiXxkj2b7AR1bHFnR1LVxli1YBd0a/L5xHljCVqYzG+OhNM5U0FLqjYO2OvRCDS6UL59bcHZ1v/OBvoHBVCa4mGGPsnHdO9I09DsgmiNaWtuC98iUjoMeTA3I6bLvt4Zt09ow4Dy7bCx8IimLPbKnr80gIHtxu65AmiK9e739pYiJIieK6puQHWrAk//8BOcTMQ4TF8PSSWaqUUrnPCIx47GhJCRzCpJuKUgxUEnJksqkwqBOFdlYpgc6nXrmJXqV4W2TP250i1MJqbA1kTzDQKaEpqw8aITCr5EpkQVNDxchZGOtGruezovBKoLoml42uW6x77B+ALKXXOcpAwAA"; // await res.Content.ReadAsStringAsync();

​

using var stream = new MemoryStream(Convert.FromBase64String(base64));

using var gZipStream = new GZipStream(stream, CompressionMode.Decompress);

​

string json;

using (var sr = new StreamReader(gZipStream))

{

    json = sr.ReadToEnd();

}

​

Console.WriteLine(json);

    }

}