MarsSeed [1] filed a deletion request for ros-melodic-openni2-launch [2]: Abandoned since 2021, flagged since 2022-07 for the last point release from Apr 12, 2022; otherwise this is EOL, with all ROS Melodic distro packages.
No one uses this and nothing depends on it. Safe to delete. [1] https://aur.archlinux.org/account/MarsSeed/ [2] https://aur.archlinux.org/pkgbase/ros-melodic-openni2-launch/
