No, it is a tool.

My IDE doesn't pretend to be a cohauthor of my work, neither should an LLM.

I'm not sure if "plagiarism" is the right word or not, but given that the output of an AI seems to be considered non-copyrightable*, and given also that a lot of people are very upset about generative AI being immoral**, I think it's important to identify which contributions are from the tools whose use may cause problems.

* I am not a lawyer, I'm going by articles talking about this

** I think the phrases are "copyright washing" and "plagiarism machines", amongst others