It all started with remarks from David Ayer about Warner Bros. and Suicide Squad while at the Comic-Con panel for his Netflix Bright movie, which also stars Will Smith.
David Ayer is quoted as stating:
I don't think people realize the situation filmmakers face ... Netflix is gonna pull a lot more talent because they're so supportive.
This isn't like, some bullshit standard issue studio PG-13 movie. I was able to do some real sh-t here."
Evidence Ayer is talking about Suicide Squad comes from the fact he has only directed one PG-13 movie, which is Suicide Squad.
To add to that, a reporter for Variety tweeted out that the Gotham City Sirens movie wasn't green lit in the first place, and insinuated that it was David Ayer leaking the movie to further his involvement in the DCEU:
Ever ask yourself Maybe this pic was leaked before because a person no longer involved SQUAD wants to still be linked to DCEU.
David Ayer is no longer involved with Suicide Squad 2 as the sequel will have a new director.
Getting back to the legitimacy of the rumor that Ayer and Gotham City Sirens isn't happening, the original article came from Mashable who has now added in an article about Zack Snyder no longer being involved with the DCEU:
Ayer's rep flatly denied that he's off the project, saying it's still in development and that the script is not yet complete.
So we see Ayer's rep shoots down the rumor; however, the article did bring up a good point in why would Ayer - if still involved with the DCEU - slam his own Suicide Squad movie and WB?
My own two cents about what David Ayer had to say about Suicide Squad at Comic-Con: I've never met the guy personally, but from what I've read and seen in interviews, David Ayer isn't one to bite his tongue and seems a rather outspoken dude. It's possible he was more or less promoting Bright and Netflix--trying to separate the movie from a PG-13 flick and get a pop from the audience. It's also been said there were issues with Suicide Squad, particularly with the ending, which possibly Ayer is alluding to, as the finished product might not have been Ayer's vision of Suicide Squad.