As reported by... well, every online news outlet, WB decided to axe the project. Reportedly, test screenings said the movie looked "cheap," despite reports refuting the decision was due to the quality of the film itself. We'll never see it since WB is writing it off, meaning they can't monetize it in any way, including an HBO Max release. I have mixed feelings. Batgirl is one of my favorite DCU characters, but I never got good vibes from the first screenshot. Costume looked cheap, like CW level cheap. I knew very little else about it because little else was ever reported. Here's the snippet from Wiki but there are tons of other articles on it.
Wikipedia: Canceled release
In August 2022, Warner Bros. Discovery (WBD) no longer planned to release the film on HBO Max or theatrically,[1][44][45][46] despite its planned release in 2022 on HBO Max,[45] making the film "effectively dead". TheWrap reported that the company felt the film "simply did not work" and went against the new desire and mandate from CEO David Zaslav to make DC films "big theatrical event films". Despite this, the company hoped to work on other projects with El Arbi and Fallah and Grace.[1] Collider added that viewers of some of the first test screenings described the film as "a huge disappointment and looked cheap in comparison to other films", which could have been a factor in Warner Bros. Discovery's decision;[47] Variety refuted this notion that the quality of the film factored into the decision,[44] reaffirming, along with The Hollywood Reporter and Deadline Hollywood, that it was part of the studio's larger cost-cutting measures, given the budget increased from its initial $70 million to $90 million, and the desire for DC films to be theatrical blockbusters.[44][45][46] A subsequent Variety report indicated that, according to sources within WBD, the company had concluded that writing off the movie for a tax break would be the most "financially sound" way of recouping Batgirl's costs, as opposed to either moving the film to a theatrical release with additional investment, selling it to another distributor, or even releasing it as-is on HBO Max.[48]
Hopefully this doesn't discourage the studio from making a new movie soon. Babs deserves it.