Access another part of a body request sent to a C# .net core app

I'm just starting to learn C# and building a service for a simple project. I am using Hasura as my API (GraphQL) and sending a Hasura action (POST webhook) to my C# app. It works by when the action mutation happens it sends the POST request. The issue I'm having is that the format of the request has a complex body.

The app works fine with just using Postman as the response is simple. The response for the Hasura is below:

{  request_query: 'mutation Mutation {\n'+'  validateName(card: "ADSADSA", email: "ADSADSA", name: "DASDADAS") {\n'+'    card\n'+'    name\n'+'    email\n'+'  }\n'+'}\n'+'\n'+'query MyQuery {\n'+'  users {\n'+'    card\n'+'    email\n'+'    id\n'+'    name\n'+'  }\n'+'}\n',  session_variables: { 'x-hasura-role': 'admin' },  input: { card: 'ADSADSA', email: 'ADSADSA', name: 'DASDADAS' },  action: { name: 'validateName' }}

This is my current C# code:

var builder = WebApplication.CreateBuilder(args);var app = builder.Build();app.UseHttpLogging(); app.MapPost("/validateName", async (User user) => {Console.WriteLine(user.name);var validateUser = new User();validateUser.name = user.name?.ToLower();validateUser.email = user.email?.ToLower();validateUser.card = user.card?.ToLower();return Results.Json(validateUser);});app.Run();class User{    public string? name { get; set; }     public string? email { get; set; }    public string? card { get; set; }}

Firstly I would like to know how do I see the response in C#. Secondly how would I access the input of the body as this is where the key data I need.