/usr/share/doc/gnome-software-plugin-flatpak/changelog.Debian.gz is in gnome-software-plugin-flatpak 3.28.1-0ubuntu4.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/share/doc/gnome-software-plugin-flatpak/../gnome-software/changelog.Debian.gz