MarsSeed [1] filed a deletion request for ros-noetic-common-msgs [2]: EOL, unused resource package. The majority of the ROS1 Noetic applications and libraries (all EOL) are not compatible with Arch Linux, only with the freshly EOL Ubuntu 20.04 LTS and Python 3.9.
[1] https://aur.archlinux.org/account/MarsSeed/ [2] https://aur.archlinux.org/pkgbase/ros-noetic-common-msgs/
