Exposed Git metadata
/.git/HEAD returned a refs/heads line, or /.git/config looked like a git config.
In plain language
The site served a Git metadata file.
An exposed .git directory lets someone reconstruct the repository, including history and deleted secrets.
A generic fix prompt
Paste this into your coding agent, or apply it by hand: Block requests to /.git on the host. If the directory was downloadable, rotate secrets that have ever been committed and assume the source is public.