showing [Object: null prototype] {} in req.cookies

I am trying to store cookie and get via cookie-parser, but only showing [Object: null prototype] {}
I am using postman to check, also using cores and body-parser

This is my index.js

const dotenv = require("dotenv");
const express = require("express");
const connectDB = require("./config");
const bodyParser = require("body-parser");
const cors = require("cors");
const cookieParser = require("cookie-parser");
const errorHandler = require("./middlewares/errorHandler");
const corsOptions = {
  origin: "http://localhost:3000",
  credentials: true,
};

dotenv.config();
connectDB();

const app = express();

app.use(bodyParser.urlencoded({ extended: true, limit: "30mb" }));

app.use(bodyParser.json());

app.use(cookieParser());
app.use(cors(corsOptions));

app.use("/v1/user", require("./routes/userRouter"));

app.use(errorHandler);
const PORT = process.env.PORT || 8000;
const server = app.listen(PORT, () => {
  console.log(`Server listening on ${PORT}`);
});

This is my user controller

login: async (req, res) => {
    try {
      const { email, password } = req.body;
      if (!email || !password)
        return res.status(400).json({ msg: "Please fill all the fields." });

      if (!validateEmail(email))
        return res
          .status(400)
          .json({ msg: "Please enter valid email address." });

      const user = await User.findOne({ email }).select("+password");
      if (!user)
        return res.status(400).json({ msg: "This email does not exist." });

      const isMatch = await bcrypt.compare(password, user.password);
      if (!isMatch)
        return res.status(400).json({ msg: "Password is incorrect." });
      console.log(isMatch);

      const refresh_token = createRefreshToken({ id: user._id });
      res.cookie("refreshtoken", refresh_token, {
        httpOnly: true,
        path: "/user/refresh_token",
        maxAge: 7 * 24 * 60 * 60 * 1000,
      });
      res.json({ msg: "Login success!" });
    } catch (error) {
      return res.status(500).json({ msg: error.message });
    }
  },
  getAccessToken: async (req, res) => {
    try {
      const rf_token = req.cookies.refreshtoken;
      console.log(req.cookies);
      if (!rf_token) return res.status(400).json({ msg: "Please login now!" });

      jwt.verify(rf_token, process.env.REFRESH_TOKEN_SECRET, (err, user) => {
        if (err) return res.status(400).json({ msg: "Please login now!" });
        const access_token = createAccessToken({ id: user.id });
        res.json({ access_token });
      });
    } catch (error) {
      return res.status(500).json({ msg: error.message });
    }
  },

In getAccessToken showing [Object: null prototype] {}

This is my package.json

{
  "name": "backend",
  "version": "1.0.0",
  "description": "",
  "main": "index.js",
  "scripts": {
    "start": "node index.js",
    "dev": "nodemon index.js"
  },
  "keywords": [],
  "author": "",
  "license": "ISC",
  "dependencies": {
    "bcryptjs": "^2.4.3",
    "body-parser": "^1.20.2",
    "cookie-parser": "^1.4.6",
    "cors": "^2.8.5",
    "dotenv": "^16.4.5",
    "express": "^4.19.2",
    "express-async-handler": "^1.2.0",
    "jsonwebtoken": "^9.0.2",
    "mongoose": "^8.3.2",
    "nodemailer": "^6.9.13"
  },
  "devDependencies": {
    "nodemon": "^3.1.0"
  }
}

I am stuck in getting cookies value, please help