Fetch request with ASP . Net Core 3.0

Question

I am trying to replace the Ajax methods by Fetch in the application, but I cannot receive an object with Fetch, I made a small test object to try to receive, in Ajax, with you passing parameter through Data

    public class ObjetoTeste
    {
        public string Nome { get; set; }
        public string NomeFantasia { get; set; }
    }

On my controller, I receive as follows

    public JsonResult Teste(long s, ObjetoTeste obj)
    {
        return Json(obj);
    }

With Ajax, I receive the object normally, already in Fetch, I can’t send anything, it always receives null in Controller, in Javascript, I set up 2 methods that receive the same object, identical, and both behave differently.

    var data = {
        s: 500,
        obj: {
            Nome: 'Nome',
            NomeFantasia: 'NomeFantasia'
        }
    }

    _private.Ajax = function () {
        console.log('Ajax')
        $.ajax({
            url: "/Home/Teste",
            type: "POST",
            data: data,
            success: function (response) {
                console.log(response)
            },
            error: function (jqXHR, textStatus, errorThrown) {
                console.log(textStatus, errorThrown);
            }
        });
    }

    _private.Fetch = function () {
        console.log('Fetch')
        fetch('/Home/Teste', {
            method: 'POST',
            body: data,
        }).then((resp) => resp.json())
        .then(function (data) {
            console.log(data)
        })
    }

It’s just an example snippet, but if it works out, I will implement the Fetch method as default in my requests.