/usr/lib/libqwtplot3d-qt5.so is in libqwtplot3d-qt5-dev 0.2.7+svn191+gcc7-2.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/lib/libqwtplot3d-qt5.so.0.2.7
/usr/lib/libqwtplot3d-qt5.so.0.2.7