Iruma is not turning small, we just keep missing the fact the SaBro is huge. Its usually not noticeable as the recent scenes of him were in the background with other characters with decent height i.e. Nee-san and Jazz, sometimes Azz-Azz.
I don’t like that picture of Iruma with the same eyes as that edgy, “I feed on your agony and despair (face),” ‘Return-to-Origin’ guy. Especially whenever he looks like he just finished having an epic dump.