Reactjs – Post request working fine in Postman but not in browser

When sending SignUp and Login data through Postman, it’s getting stored in Mongodb as well as showing success message but when requested through React axios, it is showing error in console as

POST http://localhost:1000/auth/signup 400 (Bad Request)

Below is the backend and frontend code files for reference.

.routes/auth.js

const express = require("express");
const router = express.Router();
const user = require("../models/user");
const bcrypt = require("bcryptjs");
const jwt = require("jsonwebtoken");
const {authenticateToken} = require("./userAuth");


router.post("/signup", async(req,res)=>{
    try{
        const {username,password,email} = req.body;
        const hashPass = await bcrypt.hash(password,10);
        const newUser = new user({username:username,email:email,password:hashPass});
        await newUser.save();
        return res.status(200).json({message:"SignUp successful!"})
            }
    
    catch(error){
        res.status(500).json({message:"internal server error"});
    }
});

app.js:

const express = require("express");
const app = express();
const cors = require("cors");
require("dotenv").config();
const conn = require("./conn/conn");
app.use(express.json());
app.use(cors({
    origin: 'http://localhost:5173' // Adjust to match your frontend URL
}));

conn().then(() => {
    app.use(express.json());

    app.use("/auth", require("./routes/auth")); 
    // app.use('/user', require("./routes/user"));
    app.listen(process.env.port, () => {
        console.log(`Server started at ${process.env.port}`);
    });
}).catch(error => {
    console.error("Failed to connect to database:", error);
});

Signup.jsx:

`>

import React, { useState } from "react";
import { Link, useNavigate } from "react-router-dom";
import axios from "axios";


const Signup = () => {
    const [Values,setValues] = useState({
        username: "",password:"",email:"",
    });
    const navigate = useNavigate();
    const change = (e) =>{
        const {name,value} = e.target;
        setValues({...Values,[name]:value});
    }
    const submit = async () => {
        console.log("clicked");
        try {
            if(
Values.username===""||Values.email===""||Values.password===""
            ){alert("All fields are required!");}
            else{    
                const response = await axios.post("http://localhost:1000/auth/signup", 
                Values
                );
                console.log(Values);
                navigate("/login");
            }
        
              
        } catch (error) {
            alert(error.response.data.message);
        }
    };

    return(
     // a simple signup form here to submit signup info.
    );
};

export default Signup;