/usr/share/help/de/mate-netspeed-applet/figures/loopback.png is in mate-netspeed-common 1.12.0-1.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/share/help/de/mate-netspeed-applet/figures/../../../C/mate-netspeed-applet/figures/loopback.png