LLMs are still being detected at the same level since the day coding agents were actually something, hence, it's not improving for 3 years. Why would they be undetectable next month?
If the author really did one-shot the PR, then the author must have also put in the extremely detailed and tedious work which would be required to tame LLM output for this specific repo, in which case, they actually put in real effort, applyed expertise and thoughtfulness, which is the whole issue at hand.