SvelteKit pre-rendering doesn't seem to work

This is my index.svelte

<script>

  import {prerendering} from '$app/env';

</script>

<script context="module">

  export const prerender=true;

</script>

<main>
   <h1>Hello world! prerendering : {prerendering}</h1>
</main>

I'm prerendering this page and after build, I get the pre rendered HTML file ( in the prerendered directory) with the prerendering inside h1 set to true. When I serve the app using node build and disable JS in browser, I get Hello world! prerendering : false. So clearly,the pre rendered page is not being served by the server. I am using adapter-node during build.

Any ideas why this is happening? Thank you.