In “Batman v Superman: Dawn of Justice,” the Zack Snyder-helmed film which preceded “Suicide Squad” in the DCEU’s timeline, Ben Affleck’s Batman receives a set of files stolen by Gal Gadot’s Wonder Woman from Jesse Eisenberg’s Lex Luthor. These files contain footage and information regarding other metahumans, and Batman uses them later on to assemble the first iteration of the Justice League.
However, as pointed out by Digital Spy, an inscrutable mid-credits stinger scene in “Suicide Squad” depicts Bruce Wayne cutting a deal with Amanda Waller in order to obtain paper files on the same individuals. While Waller does provide him with a file on Enchantress (Cara Delevingne), the other documents shown contain info on the Flash (Ezra Miller) and Aquaman (Jason Momoa), individuals whose identities, powers, and whereabouts are already known to Batman.
Amanda Waller knows Bruce Wayne doesn’t trust her, and the film goes to great lengths in order to prove her ruthlessness. She even asks Bruce why he would consider making a deal with her as she hands over the Justice League files. When Bruce answers that he likes “to make friends,” she replies that she doesn’t believe in friendship, only “in leverage.” Although some explanations have been presented, the idea that a person as strategic as Batman would deal with someone like Amanda Waller to obtain information he already has feels implausible.