/usr/share/man/man8/umount.crypt_LUKS.8.gz is in libpam-mount 2.14-1.1.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/share/man/man8/umount.crypt.8.gz
/usr/share/man/man8/umount.crypt.8.gz