Most of those studies call this out and try to control for it (edit: "it" here being the usual limitations of LoC and PRs as measures of productivity) where possible. But to your point, no, there is still a strong net positive effect:

> https://www.youtube.com/watch?v=tbDDYKRFjhk (from Stanford, not an RCT, but the largest scale with actual commits from 100K developers across 600+ companies, and tries to account for reworking AI output. Same guys behind the "ghost engineers" story.)

Emphasis added. They modeled a way to detect when AI output is being reworked, and still find a 15-20% increase in throughput. Specific timestamp: https://youtu.be/tbDDYKRFjhk?t=590&si=63qBzP6jc7OLtGyk