There will probably be a time when it's impossible to determine if content came from an LLM or a human. We're currently in the, "It's been 'shopped, I can tell by the pixels" stage.
If a contributor genuinely understands the problem, has tested the code themselves and writes the PR description themselves, it would be indistinguishable from human written code anyway.
Agents have us beat and we can’t win back the ground.
Or if it does, it could be hundreds of years in the future.
But maybe it'll be next year? LOL.
As it is, we seem to be developing detection techniques at a good clip and the way current LLM tech works it doesn't seem like there is a path towards avoiding detection... Plus, humans are genuinely very good at self-tuning to detect LLM output.