Note that fully AI generated content is banned, see this, and any AI assistance in making a PR must be disclosed (just like if you took some part of your PR from an external source or someone wrote a PR for you etc.)
Note that that page does not talk about the legal size of LLM generated contributions, but one of the strong reasons I, as a Godot maintainer, oppose its inclusion in the engine beyond the reasons listed there is that we simply do not know yet what the legal situation will be with generated content and I want to avoid us “poisoning” the codebase by adding code that ends up not being copyrightable and the legal mess that could cause (not to mention the legal side of plagiarism from LLMs which is also not legally established yet)