/usr/share/doc/libb64-dev/changelog.Debian.gz is in libb64-dev 1.2-4.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/share/doc/libb64-dev/../libb64-0d/changelog.Debian.gz
/usr/share/doc/libb64-dev/../libb64-0d/changelog.Debian.gz