MarsSeed [1] filed a deletion request for postgresql-12 [2]: AUR package unmaintained since May 2024. No OOD flag, seems unused.
Upstream is EOL since its last v12 release in Nov 2024. [1] https://aur.archlinux.org/account/MarsSeed/ [2] https://aur.archlinux.org/pkgbase/postgresql-12/
