I do remember some of them showed some productivity improvement but it pretty much dove off cliff with the complexity of the tasks involved, or the small improvement on medium difficulty task was eaten by time to wait for responses.

Note that most of them were focused on programming tasks aimed to ship a product, not other use cases like "prototype a dozen of ideas quickly before we pick direction", or "write/update documentation about this feature" which AI might be significantly more productive use case than just programming.