Yes. The cognitive process performed by a person using an LLM is often no different from that performed by a person using a ghost author, which is a form of plagiarism covered by 42 CFR § 93.234 - Research misconduct.
Plagiarism, at its most fundamental level, is a lie. It is the taking of works or ideas of others and passing them off as your own, either directly or indirectly. The misdeed itself is in the lie, the “I created this” when it is known to be untrue.
However, that lie isn’t being told to the original victim. It’s a lie about the victim, claiming that they didn’t create it or their contributions didn’t matter, but it’s not a lie to them. Instead, it’s a lie to the audience, which is the second victim and the actual target of the con.
https://www.plagiarismtoday.com/2019/08/01/the-two-victims-o...
This is a very good definition, but today people will just claim the AI is not a victim, and pass this argument off to the legal cases the labs are already having in court wrt fair use. It's sad, but this is the argument people have made to themselves.