/usr/lib/dovecot/libdovecot-sieve.so is in dovecot-sieve 1:2.2.22-1ubuntu2.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/lib/dovecot/libdovecot-sieve.so.0.0.0
/usr/lib/dovecot/libdovecot-sieve.so.0.0.0