/usr/share/doc/libinsighttoolkit4-dbg/changelog.Debian.gz is in libinsighttoolkit4-dbg 4.9.0-4ubuntu1.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/share/doc/libinsighttoolkit4-dbg/../libinsighttoolkit4.9/changelog.Debian.gz