brew upgrade: "Error: Unexpected method 'appcast' called on Cask font-dejavu-sans."

[findurance]

Verification

• [X] I understand that if I ignore these instructions, my issue may be closed without review.
• [X] I have retried my command with --force.
• [X] I ran brew update-reset && brew update and retried my command.
• [X] I ran brew doctor, fixed as many issues as possible and retried my command.
• [X] I have checked the instructions for reporting bugs.
• [X] I made doubly sure this is not a checksum does not match / SHA256 mismatch error (do not open an issue before trying to open a PR to fix first).

Description of issue

Homebrew constantly outputting the error about fonts-dejavu-sans, even when 'update-reset' && 'update' has been successfully run.

Command that failed

brew upgrade; brew uninstall --force dosbox; brew remove --force dosbox

Output of command with --verbose --debug

<hundreds of lines of the likes below>

/usr/local/Homebrew/Library/Homebrew/brew.rb (Formulary::FromAPILoader): loading homebrew/core/jpeg-turbo
/usr/local/Homebrew/Library/Homebrew/brew.rb (Formulary::FromAPILoader): loading homebrew/core/sdl12-compat
/usr/local/Homebrew/Library/Homebrew/brew.rb (Formulary::FromAPILoader): loading homebrew/core/libmpc
/usr/local/Homebrew/Library/Homebrew/brew.rb (Formulary::FromAPILoader): loading homebrew/core/gnutls
/usr/local/Homebrew/Library/Homebrew/brew.rb (Formulary::FromAPILoader): loading homebrew/core/berkeley-db
/usr/local/Homebrew/Library/Homebrew/brew.rb (Formulary::FromAPILoader): loading homebrew/core/sdl_net
/usr/local/Homebrew/Library/Homebrew/brew.rb (Formulary::FromAPILoader): loading homebrew/core/duktape
/usr/local/Homebrew/Library/Homebrew/brew.rb (Formulary::FromAPILoader): loading homebrew/core/qhull
/usr/local/Homebrew/Library/Homebrew/brew.rb (Cask::CaskLoader::FromAPILoader): loading balenaetcher
/usr/local/Homebrew/Library/Homebrew/brew.rb (Cask::CaskLoader::FromAPILoader): loading discord
/usr/local/Homebrew/Library/Homebrew/brew.rb (Cask::CaskLoader::FromAPILoader): loading dosbox
/usr/local/Homebrew/Library/Homebrew/brew.rb (Cask::CaskLoader::FromAPILoader): loading firefox
/usr/local/Homebrew/Library/Homebrew/brew.rb (Cask::CaskLoader::FromInstalledPathLoader): loading font-dejavu-sans
Error: Unexpected method 'appcast' called on Cask font-dejavu-sans.
Follow the instructions here:
  https://github.com/Homebrew/homebrew-cask#reporting-bugs

<more of those lines of "loading..."

Output of brew doctor and brew config

lassi@nuppi ~ $ brew doctor 
Error: Unexpected method 'appcast' called on Cask font-dejavu-sans.
Follow the instructions here:
  https://github.com/Homebrew/homebrew-cask#reporting-bugs
Error: Unexpected method 'appcast' called on Cask font-dejavu-sans.
Follow the instructions here:
  https://github.com/Homebrew/homebrew-cask#reporting-bugs
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: A newer Command Line Tools release is available.
Update them from Software Update in System Settings.

If that doesn't show you any updates, run:
  sudo rm -rf /Library/Developer/CommandLineTools
  sudo xcode-select --install

Alternatively, manually download them from:
  https://developer.apple.com/download/all/.
You should download the Command Line Tools for Xcode 15.2.

Warning: Some installed kegs have no formulae!
This means they were either deleted or installed manually.
You should find replacements for the following formulae:
  fluid-synth@2.1
  szip

Warning: Some installed formulae are deprecated or disabled.
You should find replacements for the following formulae:
  dosbox
  ilmbase
  lua@5.1
  openssl@1.1
  python-packaging
  python-ply
  python@3.8
  sdl_net
  sdl_sound

Warning: You have unlinked kegs in your Cellar.
Leaving kegs unlinked can lead to build-trouble and cause formulae that depend on
those kegs to fail to run properly once built. Run `brew link` on these:
  lua@5.1

Warning: Homebrew's "sbin" was not found in your PATH but you have installed
formulae that put executables in /usr/local/sbin.
Consider setting your PATH for example like so:
  echo 'export PATH="/usr/local/sbin:$PATH"' >> /Users/lassi/.bash_profile

lassi@nuppi ~ $ brew config
HOMEBREW_VERSION: 4.3.11
ORIGIN: https://github.com/Homebrew/brew
HEAD: 3b9bec8c9561f622bfd59e87dfebd02df07f9369
Last commit: 13 hours ago
Core tap JSON: 29 Jul 21:03 UTC
Core cask tap JSON: 29 Jul 21:46 UTC
HOMEBREW_PREFIX: /usr/local
HOMEBREW_CASK_OPTS: []
HOMEBREW_DISPLAY: /private/tmp/com.apple.launchd.ZxpMPrxQyH/org.xquartz:0
HOMEBREW_EDITOR: vim
HOMEBREW_GITHUB_API_TOKEN: set
HOMEBREW_MAKE_JOBS: 4
Homebrew Ruby: 3.3.4 => /usr/local/Homebrew/Library/Homebrew/vendor/portable-ruby/3.3.4/bin/ruby
CPU: quad-core 64-bit kabylake
Clang: 14.0.3 build 1403
Git: 2.45.2 => /usr/local/bin/git
Curl: 8.4.0 => /usr/bin/curl
macOS: 13.6.7-x86_64
CLT: 14.3.1.0.1.1683849156
Xcode: N/A

Output of brew tap

lassi@nuppi ~ $ brew tap
lassi@nuppi ~ $

[khipp]

Take a look at our pinned issue: https://github.com/Homebrew/homebrew-cask/issues/173201#issuecomment-2101662209.