Understanding how cask reachability is checked

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Output of brew config

HOMEBREW_VERSION: 6.0.11-96-g2cd4aea
ORIGIN: https://github.com/Homebrew/brew
HEAD: 2cd4aea237373f7bff2c8f9106bd6c9f3c5db247
Last commit: 2 hours ago
Branch: main
Core tap: N/A
Core cask tap HEAD: a11225f4d7d45acf56cc0b51b1f70b8708ed449c
Core cask tap last commit: 2 hours ago
HOMEBREW_PREFIX: /opt/homebrew
HOMEBREW_DISPLAY: /private/tmp/com.apple.launchd.aApoG6rPdB/org.xquartz:0
HOMEBREW_EDITOR: /opt/homebrew/bin/bbedit --new-window --wait --resume --
HOMEBREW_NO_UPGRADE_AUTO_UPDATES_CASKS: set
Homebrew Ruby: 4.0.6 => /opt/homebrew/Library/Homebrew/vendor/portable-ruby/4.0.6/bin/ruby
CPU: octa-core 64-bit arm_blizzard_avalanche
Clang: 17.0.0 build 1700
Git: 2.55.0 => /opt/homebrew/bin/git
Curl: 8.7.1 => /usr/bin/curl
macOS: 15.7.7-arm64
CLT: 26.3.0.0.1.1769666919
Xcode: N/A
Rosetta 2: false

Output of brew doctor

Warning: Some installed casks are deprecated or disabled.
You should find replacements for the following casks:
    doppler-app

Description of issue

As the output of brew doctor implies, I've got a cask which has been disabled (relevant commit) because, according to the comment in the cask file:

\ # Download url is unreachable due to Cloudflare protections

OK, fair enough. But I'd like to understand how this is determined. There's nothing in the docs about it (the :unreachable reason isn't documented at all), and I've just spent a bit of time trying to get Cloudflare to block me from accessing the download URL and it always lets me through. What if this was a transient issue and now there's no ongoing reachability problem? How can I test that?

Relevant casks

doppler-app

[bevanjkay]

This usually means that the download servers are unreachable from the GitHub CI runners. As we are unable to test the packages, we are not able to maintain them in homebrew-cask.

To test it, you would need to open a PR to remove the disable/deprecate line and see if the files can be downloaded via CI.