/usr/share/doc/libtcmalloc-minimal4-dbg/changelog.Debian.gz is in libtcmalloc-minimal4-dbg 2.4-0ubuntu5.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/share/doc/libtcmalloc-minimal4-dbg/../libtcmalloc-minimal4/changelog.Debian.gz