It's not 10x, but https://www.ft.com/content/5ac2ee5f-f8bd-4f39-a759-3c5c50c8b... has some graphs suggesting a 1.5x increase in metrics like "number of new apps published in the iOS App Store" and "lines of code committed by US GitHub users".

People haven't noticed because the software industry was already mostly unoriginal slop, even prior to LLMs, and people are good at ignoring unoriginal slop.