I don't agree. Who/what wrote the commit is definitely part of the commit.

If Git commits formally had a co-authored header, it would go there. As it stands, there is one author and one committer. If something was pair programmed, whether with a human or machine, you need a commit message trailer if you want to show that. Commit message trailers are a formal mechanism in git, supported by tooling; there are git commands to add and remove them.

Totally agree about "sent from my fartphone", of course.

Disclosing things in the pull request is not enough; pull requests get lost in the sands of time. Years down the road, all that some downstream consumer has is the git history, not any CI-related metadata.