Recent bug with language stanza in cask?

[Yann-R]

Output of brew config

HOMEBREW_VERSION: 5.0.2-50-g001e922
ORIGIN: https://github.com/Homebrew/brew
HEAD: 001e92274f1d1e14e59d28d5f7db67f1a3a2e31c
Last commit: 6 hours ago
Branch: main
Core tap JSON: 18 Nov 13:29 UTC
Core cask tap JSON: 18 Nov 13:29 UTC
HOMEBREW_PREFIX: /opt/homebrew
HOMEBREW_REPOSITORY: /opt/homebrew/Homebrew
HOMEBREW_CASK_OPTS: []
HOMEBREW_DISPLAY: /private/tmp/com.apple.launchd.4gn3hYbCnK/org.xquartz:0
HOMEBREW_DOWNLOAD_CONCURRENCY: 28
HOMEBREW_FORBID_PACKAGES_FROM_PATHS: set
HOMEBREW_MAKE_JOBS: 14
HOMEBREW_SORBET_RUNTIME: set
Homebrew Ruby: 3.4.7 => /opt/homebrew/Homebrew/Library/Homebrew/vendor/portable-ruby/3.4.7/bin/ruby
CPU: 14-core 64-bit arm_brava
Clang: 17.0.0 build 1700
Git: 2.51.2 => /opt/homebrew/bin/git
Curl: 8.7.1 => /usr/bin/curl
macOS: 15.7.1-arm64
CLT: 26.0.0.0.1.1757719676
Xcode: 26.1.1
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 casks are deprecated or disabled.
You should find replacements for the following casks:
  angry-ip-scanner
  aural
  automute
  bluegriffon
  chromium
  diffmerge
  dupeguru
  easy-move+resize
  haptic-touch-bar
  linkliar
  mkvtoolnix-app
  provisionql
  qladdict
  qlcolorcode
  qlmarkdown
  qlprettypatch
  qlstephen
  quicklook-csv
  quicklook-json
  quicklook-pfm
  seamonkey
  skype
  unison-app
  webpquicklook

Warning: Some installed formulae are deprecated or disabled.
You should find replacements for the following formulae:
  sshfs-mac
  icu4c@75
  icu4c@76
  id3tool
  webkit2png

Warning: Putting non-prefixed coreutils in your path can cause GMP builds to fail.

Warning: /usr/bin occurs before /opt/homebrew/bin in your PATH.
This means that system-provided programs will be used instead of those
provided by Homebrew. Consider setting your PATH so that
/opt/homebrew/bin occurs before /usr/bin. Here is a one-liner:
  echo 'setenv PATH /opt/homebrew/bin:$PATH' >> ~/.tcshrc

The following tools exist at both paths:
  ctags
  git
  git-receive-pack
  git-shell
  git-upload-archive
  git-upload-pack
  nano
  openssl
  pip3
  pp
  python3
  rsync
  tclsh
  trash
  wish

Description of issue

I suspect a recent misbehavior with language-dependent casks (containing language stanza) since brew upgrade replaced my localized versions by (default) English upgrades versions.

By using options --debug --verbose, I indeed observe the download of English variants instead of localized versions.

• for instance, concerning thunderbird, the following command reveals unexpected https://download-installer.cdn.mozilla.net/pub/thunderbird/releases/145.0/mac/en-US/Thunderbird\%20145.0.dmg
• similarly concerning libreoffice-language-pack, the command reveals unexpected https://download.documentfoundation.org/libreoffice/stable/25.8.3/mac/aarch64/LibreOffice_25.8.3_MacOS_aarch64_langpack_en-GB.dmg

$ echo $LANG ; brew fetch --debug --verbose thunderbird fr_FR.UTF-8 /opt/homebrew/Homebrew/Library/Homebrew/brew.rb (Cask::CaskLoader::FromAPILoader): loading thunderbird /opt/homebrew/Homebrew/Library/Homebrew/brew.rb (Cask::CaskLoader::FromAPILoader): loading thunderbird /usr/bin/env /opt/homebrew/Homebrew/Library/Homebrew/shims/shared/curl --disable --cookie /dev/null --globoff --show-error --user-agent Homebrew/5.0.2-52-gcaacda1\ \(Macintosh\;\ arm64\ Mac\ OS\ X\ 15.7.1\)\ curl/8.7.1 --header Accept-Language:\ en --retry 3 -V /usr/bin/env /opt/homebrew/Homebrew/Library/Homebrew/shims/shared/curl --disable --cookie /dev/null --globoff --show-error --user-agent Homebrew/5.0.2-52-gcaacda1\ \(Macintosh\;\ arm64\ Mac\ OS\ X\ 15.7.1\)\ curl/8.7.1 --header Accept-Language:\ en --retry 3 --fail --location --silent --head https://download-installer.cdn.mozilla.net/pub/thunderbird/releases/145.0/mac/en-US/Thunderbird\%20145.0.dmg /usr/bin/env /opt/homebrew/Homebrew/Library/Homebrew/shims/shared/curl --disable --cookie /dev/null --globoff --show-error --user-agent Homebrew/5.0.2-52-gcaacda1\ \(Macintosh\;\ arm64\ Mac\ OS\ X\ 15.7.1\)\ curl/8.7.1 --header Accept-Language:\ en --retry 3 --fail --location --silent --head --request GET --http1.1 https://download-installer.cdn.mozilla.net/pub/thunderbird/releases/145.0/mac/en-US/Thunderbird\%20145.0.dmg ==> Checking quarantine support [Downloading 142.1MB/-------] /usr/bin/env /usr/bin/xattr -h /usr/bin/env /Library/Developer/CommandLineTools/usr/bin/swift -target arm64-apple-macosx15 /opt/homebrew/Homebrew/Library/Homebrew/cask/utils/quarantine.swift ==> Quarantine is available. [Downloaded 142.1MB/142.1MB] ==> Verifying Gatekeeper status of /Users/me/Library/Caches/Homebrew/downloads/4f8027d22e925519b4fcde1f59612c25b5e9a6f7afadc8cdcb798a93dfc7ff91--Thunderbird 145.0.dmg /usr/bin/env /usr/bin/xattr -p com.apple.quarantine /Users/me/Library/Caches/Homebrew/downloads/4f8027d22e925519b4fcde1f59612c25b5e9a6f7afadc8cdcb798a93dfc7ff91--Thunderbird\ 145.0.dmg ==> /Users/me/Library/Caches/Homebrew/downloads/4f8027d22e925519b4fcde1f59612c25b5e9a6f7afadc8cdcb798a93dfc7ff91--Thunderbird 145.0.dmg is quarantined ==> Verifying checksum for '4f8027d22e925519b4fcde1f59612c25b5e9a6f7afadc8cdcb798a93dfc7ff91--Thunderbird 145.0.dmg' ✔︎ Cask thunderbird (145.0)

Relevant casks

thunderbird, libreoffice-language-pack

[SMillerDev]

See Homebrew/brew#21094

[Yann-R]

Oh, yes, I missed this bug-report posted after my own search for the bug.
it gives a solution, many thanks @SMillerDev.