Pangram, and any tool like it, faces an uphill battle that's ultimately unwinnable. It assumes a static definition of "AI-generated" content, but as yen223 pointed out, there's no inherent "humanity" quality that can't be mimicked. This cat-and-mouse game between detectors and generators will heavily favor the generators. We've seen this play out in other security domains; the attacker always evolves faster than the defender.