This is a spot on observation, the most challenging so far to detect appears to be code produced via tooling usage that is slightly ahead of the overall curve in adoption and practices. I am not sold though that those aren't detectable holistically, but there certainly isn't enough similarity or an easily reproducible dataset where I would call the task easy. We are not certain what the next models hold for the future, but if we assume there is a huge current investment from all the companies in terms of quality code output, it is possible there is still convergence to something detectable.