/usr/share/doc/libidn11-dev/AUTHORS.gz is in libidn11-dev 1.23-2.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/share/doc/libidn11-dev/../libidn11/AUTHORS.gz
/usr/share/doc/libidn11-dev/../libidn11/AUTHORS.gz