Option usecreateindex is not supported

I am trying to connect mongoDB to my web app but it is saying that usercreateindex is not supported please help me with this

This is the code from my index.js file

const express = require('express');
const app = express();
const mongoose = require('mongoose');


const connection_string = process.env.CONNECTION_STRING
//const port = process.env.PORT || 80

app.get('/', (req, res) => {
    res.send("Welcome to our ToDo")

app.listen(80,() =>{
    console.log("Server running on port 80.")

mongoose.connect(connection_string, {
    useNewUrlParser: true,
    useCreateIndex: true,
    useUnifiedTopology: true

.then(() => console.log('MongoDB connection established.'))
.catch((error) => console.error("MongoDB connection failed:", error.message))

this is code from my .env file:

CONNECTION_STRING = mongodb+srv://USER:PASSWORD@cluster0.zzz.mongodb.net/toDoApp?retryWrites=true&w=majority