/usr/lib/x86_64-linux-gnu/libRivet.so.11 is in librivet11v5 1.8.3-2build1.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/lib/x86_64-linux-gnu/libRivet.so.11.0.1
/usr/lib/x86_64-linux-gnu/libRivet.so.11.0.1