why is 'body' empty in nodejs express post request?

I'm trying to catch raw data in the body that's sent by Postman. This is the raw data:

{
    "hello": "world"
}

I'm using app.use(express.json()) in the server. When I send the post request I just get an empty JSON. Why is this happening?

App.js code:

import express from "express"
import { connectDb } from "./connectDb.js"
import create from "./routes/create.js" // router

const app = express()
app.use(express.json())

connectDb()

const PORT = process.env.PORT || 5000

app.use("/api", create)

app.listen(PORT, () => console.log(PORT, "Connected..."))

Router Code:

import express from "express"
import Game from "../models/gamesModel.js" // mongoose model
const router = express.Router()

router.route("/create/game").post(async (req, res) => {
  console.log(req.body)
  try {
    const game = await Game.create(req.body)
    res.json(game)
  } catch (error) {
    res.json({ message: "Invalid Information" })
  }
})