I have no sensitive settings about the field (like the image field where you can chose how the field is displayed : array, url or id).
I can just chose label, name, type (gallery), instructions, required, minimum and maximum selection, insert, library, restriction on size image, allowed file type, conditional logic and wrapper attribut.
I don’t see what can change how the field is returned.
Welcome to the Advanced Custom Fields community forum.
Browse through ideas, snippets of code, questions and answers between fellow ACF users