/usr/share/doc/thunderbird-locale-zh-hant/changelog.Debian.gz is in thunderbird-locale-zh-hant 1:52.7.0+build1-0ubuntu1.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/share/doc/thunderbird-locale-zh-hant/../thunderbird/changelog.Debian.gz