/usr/share/doc/gir1.2-flatpak-1.0/changelog.Debian.gz is in gir1.2-flatpak-1.0 0.11.3-3.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/share/doc/gir1.2-flatpak-1.0/../libflatpak0/changelog.Debian.gz