/usr/lib/x86_64-linux-gnu/libappindicator.so is in libappindicator-dev 0.4.92-4.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/lib/x86_64-linux-gnu/libappindicator.so.1.0.0
/usr/lib/x86_64-linux-gnu/libappindicator.so.1.0.0