MockAPI doesn’t receive data as expected

I’m using mockAPI to create an api for my project, but when i use .POST method to send data, mockAPI doesn’t receive it.

Data I send

const product = {
    "address": "commune, district, province",
    "date": "24/10/2022",
    "email": "[email protected]",
    "id": 3879042658,
    "name": "Mr. Cabin",
    "note": "please take care",
    "phone": "1234567890",
    "products": [
        {id: 1, soLuong: 3}
    ]
}]

I use fetch to send data

function addOrders() {
    fetch('API-MOCKAPI URL', {
        method: 'POST',
        body: JSON.stringify(product)
    .then(res => res.json())
    .then(result => {
        console.log(result)
    })
}

Response I receive

{id: 64, name: 'name 3', email: 'email 3', phone: 'phone 3', address: 'address 3', product: []}