What do you do if Apple cannot verify the display as genuine? And what action is required to rectify this problem/situation?

If the ear piece was replaced, the entire display was replaced. They are a single unit that are glued together. Replace one, replace both. Your screen was replaced by a third party. That prompt is expected because they did not use a genuine part.

Did you have the screen replaced and if so, where? Do you have the receipt for that?

If that is not an Apple authorized service center, then Apple will not provide any service.