/usr/lib/x86_64-linux-gnu/libevent_extra-2.1.so.6 is in libevent-extra-2.1-6 2.1.8-stable-4build1.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/lib/x86_64-linux-gnu/libevent_extra-2.1.so.6.0.2
/usr/lib/x86_64-linux-gnu/libevent_extra-2.1.so.6.0.2