external javascript file is loading on localhost but not on proper server - node.js

When I load my node.js application using localhost, index.html’s script works properly:

<script src="/index.js" defer></script>

On the other hand, when I use render.com to load my app, index.html loads along with the css however the javascript doesn’t and this error appears in the console:

Despite the location of the file being correct as evidenced by local host working, the online host doesn’t. Other htmls that dont use javascipt work though. How would I go about fixing this?

I tried using postman through the server based url (https://blackjack-v7lr.onrender.com/index.js) but that didn’t find the file either only when using localhost did it find it

I have tried also checking if .gitignore has index.js there as this would block render.com from being able to find the file but it is not in .gitignore