Flash is for all intents and purposes a better movie but it just was not as marketable as Black Adam was. The timing was better as the DC iirc wasn’t announced to be rebooted yet, Snyder fans were excited by the announcement that Henry Cavill is back, and The Rock has a much larger fan base than a troubled Ezra Miller. The Flash has to truly be one of the top CMBs for it to have had a chance the more you look back at it.