Well you would think if there is increased productivity there would be at least a couple studies, some clear artifacts, or increased quality of software being shipped.

Except all we have is "trust me bro, I'm 100x more productive" twitter/blog posts, blant pre-IPO AI company marketing disguised as blog posts, studies that show AI decreases productivity, increased outages, more CVEs, anecdotes without proof, and not a whole lot of shipping software.