Reproduction of Next.js sourcemaps issues

npm install
npm run build
npm run start

Open the app in the browser (localhost:3000), open the devtools and navigate through the pages. If you try to open (in the source panel) the sourcemaps relative to the /content/[subject]/[method]/index.page.tsx page, you will see that the sourcemaps are not there (chrome will show a 404 error).

This happens to all the index.page.tsx pages with a dynamic route ([whatever]) with a level deeper than 1. Note that it doesn't happen in a page that has a name different than index (e.g. /content/[subject]/[method]/named.page.tsx)

Expected behavior

The sourcemaps should be there and should be correctly mapped to the original source files for all the pages, no matter the dynamic nesting level.