Working with Configuration Files

The quote below is from the CI v4 documentation. Specifically, from the last paragraph of the Handling Different Environments section.

I want to know if the line I put in bold is accurate. I don't see anything in the source code that would make the statement true.

When your application runs, this file will be automatically loaded and the variables will be put into the environment. This will work in any environment except for production, where the variables should...

Perhaps the sentence relates to a past, possibly abandoned goal and the docs have not caught up?
Or is it a reference to a yet-to-be-implemented behavior?

(Also possible: I completely misunderstand what's being said.)