MarsSeed [1] filed a deletion request for at-spi2-atk-git [2]: Upstream repo got discontinued and archived in 2022 [a] in favor of at-spi2-core. (The latter is available in Arch/extra, and there is a corresponding git package in AUR).
[a]: https://gitlab.gnome.org/GNOME/at-spi2-atk.git [1] https://aur.archlinux.org/account/MarsSeed/ [2] https://aur.archlinux.org/pkgbase/at-spi2-atk-git/
