Most /modules/* URLs are not rendered with fastboot

I've noticed a difference between pages like https://api.emberjs.com/ember/release/classes/application/ and https://api.emberjs.com/ember/release/modules/@ember%2Fapplication

The former has the pre rendered HTML response, however, the latter does not and requires Ember to bootup and render the page. This is more of a question as to why this difference? The reason I am asking is because I maintain the Ember docs in devdocs.io (https://github.com/freeCodeCamp/devdocs) and this is causing most of the documentation to not be processed. Devdocs works by scraping the HTML. In the cases of the `modules` URLs the response is missing the pre-rendered HTML and the scraper is unable to get any of the documentation. This used to work, but has changed in the last 1-2 years.

I don't know fastboot very well so I'm not sure where to start investigating this, but until this is fixed I will be unable to add documentation for 5.x and update the 4.x documentation to the latest.