/usr/share/man/man8/atk6-implementation6d.8.gz is in thc-ipv6 2.5-3.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/share/man/man8/thc-ipv6.8.gz
/usr/share/man/man8/thc-ipv6.8.gz