/usr/lib/fst/8/const64-fst.so is in libfst8-plugins-base 1.6.3-2.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/lib/fst/8/const64-fst.so.0.0.0
/usr/lib/fst/8/const64-fst.so.0.0.0