brew update|upgrade - bug or not?

[cschueller]

Output of brew config

HOMEBREW_VERSION: 5.0.4
ORIGIN: https://github.com/Homebrew/brew
HEAD: 138341781728c93d3886a9d680445d7996682e2a
Last commit: 6 days ago
Branch: stable
Core tap JSON: 06 Dec 22:59 UTC
Core cask tap JSON: 06 Dec 22:59 UTC
HOMEBREW_PREFIX: /opt/homebrew
HOMEBREW_CASK_OPTS: []
HOMEBREW_DOWNLOAD_CONCURRENCY: 16
HOMEBREW_EDITOR: vim
HOMEBREW_FORBID_PACKAGES_FROM_PATHS: set
HOMEBREW_MAKE_JOBS: 8
Homebrew Ruby: 3.4.7 => /opt/homebrew/Library/Homebrew/vendor/portable-ruby/3.4.7/bin/ruby
CPU: octa-core 64-bit arm_blizzard_avalanche
Clang: 17.0.0 build 1700
Git: 2.52.0 => /opt/homebrew/bin/git
Curl: 8.7.1 => /usr/bin/curl
macOS: 26.1-arm64
CLT: 26.1.0.0.1.1761104275
Xcode: N/A
Rosetta 2: false

Output of brew doctor

Your system is ready to brew.

Description of issue

brew update shows no updates

brew upgrade installs updates

I'm a little bit confused 🤷‍♂️

brew update
==> Updating Homebrew...
Already up-to-date.
❯ brew upgrade
==> Upgrading 2 outdated packages:
tmuxinator-completion 3.3.6 -> 3.3.7
tmuxinator 3.3.6 -> 3.3.7
==> Fetching downloads for: tmuxinator-completion and tmuxinator
✔︎ Bottle tmuxinator-completion (3.3.7)                                                                               [Downloaded   14.4KB/ 14.4KB]
✔︎ Bottle tmuxinator (3.3.7)                                                                                          [Downloaded  206.7KB/206.7KB]
==> Upgrading tmuxinator-completion
  3.3.6 -> 3.3.7
==> Pouring tmuxinator-completion--3.3.7.all.bottle.tar.gz
🍺  /opt/homebrew/Cellar/tmuxinator-completion/3.3.7: 9 files, 41.1KB
==> Running `brew cleanup tmuxinator-completion`...
Disable this behaviour by setting `HOMEBREW_NO_INSTALL_CLEANUP=1`.
Hide these hints with `HOMEBREW_NO_ENV_HINTS=1` (see `man brew`).
Removing: /opt/homebrew/Cellar/tmuxinator-completion/3.3.6... (9 files, 41KB)
==> Upgrading tmuxinator
  3.3.6 -> 3.3.7
==> Pouring tmuxinator--3.3.7.all.bottle.tar.gz
🍺  /opt/homebrew/Cellar/tmuxinator/3.3.7: 120 files, 545.9KB
==> Running `brew cleanup tmuxinator`...
Removing: /opt/homebrew/Cellar/tmuxinator/3.3.6... (120 files, 545.7KB)

[botantony]

brew upgrade updates installed packages (formulae/casks). brew update updates Homebrew itself and fetches newest data about packages. It is somewhat similar to other package managers (f.e. apt update and apt upgrade have exactly the same meaning)