node app on shared hosting cpanel cannot connect to mongodb

I have been trying to connect to mongodb via my node app on a shared hosting cpanel but it only responds with error code 503 and logs "db.collection undefined" to the console, which means the connection was not successful.

This is the database connection in db.js:

const { MongoClient } = require('mongodb');
require('dotenv').config();
let dbConnection;
 

 module.exports = {
     connectToDb: (cb) => {
    MongoClient.connect(`mongodb+srv://Achifa:${process.env.PASSWORD}@cluster0.exp9r.mongodb.net/?retryWrites=true&w=majority`)
    .then((client) => {
        dbConnection = client.db('newsDb')
        return cb()
    })
    .catch(err => {
        console.log(err)
        return cb(err)
    })
},
getDb: () => dbConnection
}

This is the app connection in app.js:

const {connectToDb, getDb} = require('./db');
let db;
var port = process.env.PORT || 50500;

connectToDb((err) => { 
   if(!err){
      var server =  app.listen(port, () => console.log("connected")); 
      db = getDb();
   }
 })