@pyrrho I appreciate your answer 
@Paulo I'm not sure when this was updated, but it appears that there are now two types of REST APIs you can create within an app editor page.
As far as I remember, there was only one method: creating app-exclusive REST APIs (please correct me if I'm wrong). However, I now see that you can also create a new resource directly in the app editor page.
(I was aware that you could create a REST API in the Resources tab.)
Two Types of REST API Resources
- Resources Tab (universal throughout the project)
- Ad-hoc (non-universal)
I have been using the ad-hoc version since this API is only needed for this specific app and not for any others. Additionally, the Resources tab suggests that these resources are meant to be defined for universal use across multiple apps.
Apparently, there is no way to switch the environment when a query in the Resources tab is not used.
To be honest, the main purpose of this post was to confirm if this is indeed the case.
I also appreciate the helpful response that included screenshots. Thank you for the detailed information 