@Dominions Son
what suspense/drama could possibly be spoiled?
If an author writes a scene to create suspense/drama, then that is the suspense/drama that will be undermined by telling the reader at that point in the story that there is no need to be concerned because . . .
@BK69
It's totally ok to reveal information that the MC later acquired, but only if it's made clear the MC didn't have it at the time.
I agree it is proper to tell the reader at the appropriate time on the story's timeline that the MC didn't have the information. However, I believe the proper time is when the author reveals the results of the earlier scene.
@LupusDei
Say, wrapping up a side plot after a point it is no longer profitable for the main tread to explore, or providing closure for characters leaving the story.
I basically agree. Clarifying the result of a scene, side plot or major plot, when the result of the scene is being addressed at a point later in the storyline is the proper place to provide the closure. If the storyline does not address the result of the plot, then it is appropriate to address the result as part of an epilog if the plot is not to be addressed in a sequel.
I also have to ask - Why the author created the scene if it is not important to the storyline? In other discussions, it was considered improper to add unnecessary text to a story. However, it is proper to add text when that text is to create doubt in the reader's mind as to what will happen in future chapters, and thus the text is important to the storyline.