Junio C Hamano, the creator of Git, believes that it is not a good practice to include the public key used to sign things in the repository itself. Despite this, Git includes the maintainer’s public key, which is hidden in the git object database. Junio’s public key is tagged as junio-gpg-pub and can only be viewed with the git cat-file command. However, in 2021, Junio stated that this was a bad idea. In a clever move, the author of the article created an empty GitHub repository called hidden-zangief, which actually contained sweet ANSI art of Zangief from Street Fighter II. By misusing some git plumbing commands, the author was able to make this fake empty repository and hide it in the refs/atomic/piledriver namespace, making it invisible in the GitHub UI. The article suggests that there is infinite magic to be discovered by developers willing to abuse git plumbing.
https://tylercipriani.com/blog/2023/07/31/git-files-hidden-in-plain-sight/