When Wonder Woman was introduced as the most experienced hero of the DCEU’s Trinity, we learned why she did nothing to stop Zod during the Black Zero Event (the Man of Steel battle and reveals played an important role in Batman v Superman: Dawn of Justice). Diana Prince said that she walked away from mankind a hundred years ago, because man made it impossible for the world to be united.
When Wonder Woman was released, we expected that the WWI events would clarify why the superheroine chose to leave Man's world behind. However, the Patty Jenkins movie demonstrated that Wonder Woman continued to protect the world from the shadows (in the sense that no one was aware of her actions).
While promoting Justice League in China, Gal Gadot said that the superheroine's backstory had evolved from Batman v Superman: Dawn of Justice to Wonder Woman, and added that sometimes first decisions aren't necessarily the correct ones. Basically, the actress admitted that the line from Batman v Superman was retconned (as Wonder Woman's history was).
In a creative process, you establish something that is not necessarily the right decision, but then you can always correct it and change it.
Then, while promoting Justice League in London, the actress seemed to backtrack, saying that Wonder Woman left mankind behind in the sense that she operated incognito (as she did in her solo movie). Her words couldn’t be more different from what she’d said in China:
What is clear is whether or not Wonder Woman was out there or incognito, she was always very involved and she was always very active in man's world and she was always acting to save, to help, and to better the world (Screen Rant).
Leaving aside the apparent contradiction, this does open up a number of possibilities. It’s now clear that Wonder Woman 2 can take place at the height of the Cold War, with the Amazonian Princess as a spy the world has never heard of (thus, a pretty great spy).
Justice League will be released on November 17. Wonder Woman 2 is scheduled for release on December 13, 2019.