the buster version of sysvinit initscripts still mounts the with /run/shm as the mount point for the tmpfs and /dev/shm as a symlink.
just adding on to the discussion...the situation actually prevents running certain flatpak applications. modifying mount-functions.sh per the attached will reverse the situation, although there is still some migration code in there that strictly speaking isn't necessary.
mount-functions.sh-testing-antix-rev1.tar.gz
Description: GNU Zip compressed data
