/usr/lib/x86_64-linux-gnu/libgnunetregex.so.3 is in gnunet 0.10.1-5build2.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/lib/x86_64-linux-gnu/libgnunetregex.so.3.0.1
/usr/lib/x86_64-linux-gnu/libgnunetregex.so.3.0.1