/usr/lib/x86_64-linux-gnu/libFS.so is in libfs-dev 2:1.0.5-1.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/lib/x86_64-linux-gnu/libFS.so.6.0.0
/usr/lib/x86_64-linux-gnu/libFS.so.6.0.0