The way you describe it, the developers all did the right thing. You contributed something to the patch, and even if it wasn't in your preferred final form (and it's basically never going to be for a kernel contribution of any significance), you were correctly credited.
If you didn't want to be credited you should have said.
Signed-off-by probably has some legal weight. When you add that to code you are making a clear statement about the origins of the code and that you have legal authority to contribute it - for example, that you asked your company for permission if needed. As far as I know none of this has been tested in court, but it seems reasonable to assume it might be one day.
The problem is they've got a doc that declares "when you say balacalaboozy, you're declaring that a specific set of legal conditions is met. You must say balacalaboozy to proceed."
Newcomers see everyone saying balacalaboozy, so they say it to. It doesn't mean that they have read or agree to the doc that declared its meaning.
LLMs are the world's most sophisticated copycats. Surely they too will parrot balacalaboozy, unless their training is updated to include, understand, and consistently follow these new guidelines.
You can write in AGENTS.md to ask the user for explicit sign off and to explain the document to the user.
> You contributed something to the patch, and even if it wasn't in your preferred final form (and it's basically never going to be for a kernel contribution of any significance), you were correctly credited.
I don't see how the "signed-off-by" attestation constitutes correct credit here. It's claiming that GP saw the final result and approved of it, which is apparently false.
Signed-off-by is a chain. The second person asserts that they delegate to the first person for the parts contributed by the first, and signs off on the ones that were contributed personally.
Hypothetically in court you'd go to the last, ask "did you write this" and only if not go up.