https://www.polygon.com/comics/2018/7/5/17536922/superman-costume-change-brian-michael-bendis-man-of-steel

Brian Michael Bendis’ Man of Steel, a prelude to his imminent storylines in Action Comics and Superman, has been a story framed by mysteries. Who is the barbaric alien warrior, Rogol Zaar, who has suddenly appeared? Where are Superman’s wife and son, Lois Lane and Jon Kent, who seem to have disappeared?

Next to those mysteries, the question of why Superman suddenly started wearing his costume with the red trunks, instead of the trunk-less one he’s worn since 2011, could have been just another thing to hand-wave away, like the idea that nobody recognizes Clark Kent when they see Superman.