MarsSeed [1] filed a deletion request for copasi [2]: Abandoned, outdated prebuilt binary-based package from 2022. Upstream is free open-source software.
I suggest that it is enough to keep AUR/copasi-bin [a], which correctly named, actively maintained, and up-to-date. [a]: https://aur.archlinux.org/pkgbase/copasi-bin [1] https://aur.archlinux.org/account/MarsSeed/ [2] https://aur.archlinux.org/pkgbase/copasi/
