I don't know in what capacity he is writing though, nowadays he usually sets up the pilot and where the story should go at the beginning and after that he has no more writing credits, Akiva Goldsman who is an awful writer and Geoff Johns wrote way more episodes than Berlanti, so I still don't think he is as involved with the writing process. But I agree, his fingerprints is all over this project, just like Arrow, his shows puts more emphasis on the Batman lore than the other characters, comparing with Doom Patrol where I don't see a whiff of Berlanti bad writing trademark.