I’m guessing it’s also the cause of the JavaScript using inline source maps, meaning that it’s shipping over 2MB to do⸺ I think it’s currently literally nothing but the click handler to expand the FAQs (which would be better not collapsed in the first place, or failing that, implemented with the <details> element).

No, that's (typically; in the default setup, at the very least; you could manage to make them related but it'd be a bit silly and take specific efforts) independent of APP_DEBUG.