MarsSeed [1] filed a deletion request for ros-noetic-convex- decomposition [2]:
Unused package from 2020. Upstream is EOL since same year. [a] [a]: https://github.com/ros/convex_decomposition [1] https://aur.archlinux.org/account/MarsSeed/ [2] https://aur.archlinux.org/pkgbase/ros-noetic-convex-decomposition/
