Raising here, as it seems more appropriate than cirruslabs/cirrus-ci-docs#878.
Bintray has been shut down Homebrew/discussions#691, forcing dependencies to be built from source or fail. In our case, this adds more than 30 minutes to the CI times unless brew update-reset is ran first (which still adds ~5 minutes compared to baseline).
Upstream Homebrew migrated all packages to GitHub packages in April, but Cirrus's images have not yet been rebuilt with this bundled.