MarsSeed [1] filed a deletion request for ros-noetic-nodelet-core [2]: Abandoned, unused, obsolete. Unmaintained on AUR since 2021. ROS1 Noetic is now EOL. Most of this distro's applications are not compatible with Arch Linux anymore, 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-nodelet-core/