There are spoilers for Justice League #52 here.
In Action Comics #957 and #958, we have seen the Pre 52 fighting the New 52 Lex Luthor in Metropolis, first against each other, and then combined against Doomsday, while Mr Oz/Ozymandia watches. And, somehow, Clark Kent is there too.
Superman wants the other Superman's cape back. But how did he get it? Well, today's Justice League #52 actually reveals something else that has been going on behind the scenes on the DC Rebirth universe. That the Daily Planet had receipt of the cape in question. And to get it, Lex Luthor had to spend a lot of money.
Lex Luthor is now only a new Superman, he owns the Daily Planet. And that's how he owns the cape. Something none of the Superman titles have got round to mentioning yet…
Justice League #52 is published today.