/usr/lib/x86_64-linux-gnu/libstartup-notification-1.so.0 is in libstartup-notification0 0.12-1ubuntu1.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/lib/x86_64-linux-gnu/libstartup-notification-1.so.0.0.0