MarsSeed [1] filed a deletion request for mono-nightly [2]: Unmaintained nightly package. Last updated on 2022-03-07. Not useful to keep as is. It is much older now than the stable 'mono' package. [1] https://aur.archlinux.org/account/MarsSeed/ [2] https://aur.archlinux.org/pkgbase/mono-nightly/