How do I find out why a formula was removed?

[Mahoney]

Output of brew config

HOMEBREW_VERSION: 4.2.15
ORIGIN: https://github.com/Homebrew/brew
HEAD: 92a4311868322188478d7a90511ec0e8e6b0d7df
Last commit: 2 days ago
Core tap JSON: 26 Mar 12:30 UTC
Core cask tap JSON: 26 Mar 12:30 UTC
HOMEBREW_PREFIX: /opt/homebrew
HOMEBREW_CASK_OPTS: []
HOMEBREW_DISPLAY: /private/tmp/com.apple.launchd.nPJ7xEebUT/org.xquartz:0
HOMEBREW_MAKE_JOBS: 10
Homebrew Ruby: 3.1.4 => /opt/homebrew/Library/Homebrew/vendor/portable-ruby/3.1.4/bin/ruby
CPU: 10-core 64-bit arm_firestorm_icestorm
Clang: 15.0.0 build 1500
Git: 2.44.0 => /opt/homebrew/bin/git
Curl: 8.4.0 => /usr/bin/curl
macOS: 14.4.1-arm64
CLT: 15.3.0.0.1.1708646388
Xcode: 15.3
Rosetta 2: false

Output of brew doctor

Please note that these warnings are just used to help the Homebrew maintainers
with debugging if you file an issue. If everything you use Homebrew for is
working fine: please don't worry or file an issue; just ignore this. Thanks!

Warning: Some installed kegs have no formulae!
This means they were either deleted or installed manually.
You should find replacements for the following formulae:
  python-pathspec

Description of issue

I've got yamllint installed, which depends on python-pathspec, which has been removed - see output of brew doctor above.

Consequently I cannot brew uninstall python-pathspec:

Refusing to uninstall /opt/homebrew/Cellar/python-pathspec/0.12.1
because it is required by yamllint, which is currently installed.

yamllint documents using brew to install it so presumably they expect their formula to work, so I'd like to report it as an issue for them, but it would be nice to be able to explain why their dependency has disappeared at the same time.

I tracked down the PR #166358 but it provides no rationale for the removal.

So my meta question is what's the right way to ensure people can work out why a formula was removed, so they can work out what (if anything) to do about it?

I found Removal, but as far as I could see the formula hadn't been deprecated or disabled

[Mahoney]

And a brew reinstall yamllint removes the dependency so I can brew uninstall python-pathspec... that seems odd? I had done a brew update && brew upgrade, so why did I need to do a reinstall of a formula?

[p-linnane]

This is a special case where there is an ongoing project to stop using dedicated formulae in place of PyPI resources: Homebrew/homebrew-core#157500

[Mahoney]

Thanks - wouldn't a link to that issue in the PR, allowing those knowing nothing about it to follow the reasoning back, have made sense?