Postman: SyntaxError: Unexpected number in JSON at position 1 at JSON.parse

I am a beginner at web development and I am trying to use Postman to send a POST request to one of my application's APIs.I am using the Next.JS framework to build my website.

Here is my API:

import type { NextApiRequest, NextApiResponse } from "next"export default async (    req: NextApiRequest,    res: NextApiResponse,) => {    const userData = JSON.parse(req.body)    res.status(200).json(userData)}

I simplified my API until I caught the error, and I believe that it is related to the JSON.parse(req.body) line.

This is a print of the data that I used to test the API on Postman

I get the following error:

SyntaxError: Unexpected number in JSON at position 1at JSON.parse (\u003canonymous\u003e)at __WEBPACK_DEFAULT_EXPORT__ (webpack-internal:///(api)/./pages/api/login.ts:9:27)

Previously, I used this API to authenticate users, and everything worked fine, except when I tried to insert data into the body of a Postman POST request.

Can someone help me? I have no idea what to do.