I keep on finding pre-commit configs in various projects which are pointed at https://gitlab.com/pycqa/flake8
It would be awesome if I could turn on a hook which checks for hooks from that repo and flags them as needing an update to the github repo. The same holds for many repos like black which have moved/renamed, and which only work because of github redirects.

I don't know if this is a common case other than flake8, or if it's so common that such a hook would be a huge pain to maintain. But it just needs to be able to read the pre-commit config and pull out the repos, not the rest of the config. It can skip support for old configs (top-level list) and make other simplifying assumptions as necessary.