The update refreshes omarchy-keyring before the system upgrade
An update left omarchy-keyring inside the system upgrade, so pacman checked signatures against the keyring already installed. A change merged into quattro puts omarchy-keyring on the refresh that already runs before that upgrade, and does nothing while the installed keyring is current.
An update refreshed the Arch keyring before the system upgrade and left omarchy-keyring to arrive inside the main transaction, so pacman checked signatures against the keyring already installed. A change merged into quattro puts omarchy-keyring on that same refresh. It installs only a newer version, and does nothing while the installed keyring is current.
Nothing changes for a user until a newer omarchy-keyring is published. It then installs before the system upgrade instead of during it. emirb ran the update on two copies of a stable image, each with a newer keyring that added one key and a package signed only by that key. With the old script the upgrade stopped and installed nothing.