I don’t need external research to validate or invalidate my own experience.

Honestly, that is a “skill issue” as the kids these days say. When used properly and with skill, agents can increase your productivity. Like any tool, use it wrong and your life will be worse off. The logically consistent view if you want to believe this study and my experience is that the average person is hindered by using AI because they do not have the skills, but there are people out there who gain a net benefit.