/usr/lib/x86_64-linux-gnu/libcsfml-system.so.2.3 is in libcsfml-system2.3 2.3-2build1.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/lib/x86_64-linux-gnu/libcsfml-system.so.2.3.0
/usr/lib/x86_64-linux-gnu/libcsfml-system.so.2.3.0