/usr/share/doc/proftpd-mod-ldap/changelog.Debian.gz is in proftpd-mod-ldap 1.3.5a-1build1.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/share/doc/proftpd-mod-ldap/../proftpd-basic/changelog.Debian.gz