Let's also not forget the multiple other studies that found significant boosts to productivity using rigorous methods like RCTs.
However, because these threads always go the same way whenever I post this, I'll link to a previous thread in hopes of preempting the same comments and advancing the discussion! https://news.ycombinator.com/item?id=46559254
Also, DX (whose CTO was giving the presentation) actually collects telemetry-based metrics (PR's etc.) as well: https://getdx.com/uploads/ai-measurement-framework.pdf
It's not clear from TFA if these savings are self-reported or from DX metrics.