tl;dr: Homebrew 6.0.0 introduces "tap trust," requiring explicit user approval before third-party taps can execute arbitrary Ruby code, alongside Bubblewrap sandboxing on Linux to match macOS isolation. The internal JSON API is now default for faster updates, and developer defaults now include "ask" confirmation prompts and parallel `brew bundle` installs. Other notable additions include initial macOS 27 (Golden Gate) support, a new `brew vulns` command for checking known vulnerabilities, performance improvements (~30% faster `brew leaves`), and three patched security advisories—while the brew-rs Rust frontend experiment was abandoned after benchmarks failed to show real-world gains.