You are using macOS 13. We (and Apple) do not provide support for this old version. This is a Tier 3 configuration: https://docs.brew.sh/Support-Tiers#tier-3 You can report Tier 3 unrelated issues to Homebrew/* repositories! Read the above document instead before opening any issues or PRs.

pkgconf 2.5.1 is already installed and up-to-date. To reinstall 2.5.1, run: brew reinstall pkgconf