/usr/lib/x86_64-linux-gnu/libqtxdg.so is in libqtxdg0-dev 0.5.2-4.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/lib/x86_64-linux-gnu/libqtxdg.so.0
/usr/lib/x86_64-linux-gnu/libqtxdg.so.0