A local guy who is involved in film tracking in Hollywood was on a show I listen to and he was asked about the Batgirl situation. Now admittedly he is not a fan of streaming and openly mocks the Netflix model (btw everything he has said has come true about it) but that is not painting his answer on why he thinks this happened. He didn't get deep into details but between the supposedly bad testing of Batgirl and the fact that to fix what needed fixing was going to likely cost another $20-30 million for a film that had no chance at a theatrical release and that that was suicide. Basically said that between the money lost on the COVID Slate and the money thrown at these "HBO Max exclusives" that WB was looking at billions in losses (he said they lost over a billion on the Slate and pumped at least as much in small projects after the fact with no way to recoup it) and Zazlov is not tied to streaming as much anyways for these types of productions because the money is just too small. If all that had been handled better Batgirl likely survives but they will make more canning it than they would putting it on Max and right now they need stuff off the books. (somewhere Mel Brooks is proud!) From the sounds of it Kilar and the previous power team was just burning money hoping against hope it would lead to Max covering for the red ink. Of course the problem is they also botched the Max launch in epic fashion so...
I have no idea if Zazlov is a good guy to have in charge, he might flame out in ridiculous fashion but one thing is for sure, he isn't going to just sit around and let amateurs try and set money on fire in hopes of heating up the box office.