/usr/lib/x86_64-linux-gnu/libinftextgtk3-0.6.so is in libinfinity-0.6-dev 0.6.7-1build1.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/lib/x86_64-linux-gnu/libinftextgtk3-0.6.so.0.0.0
/usr/lib/x86_64-linux-gnu/libinftextgtk3-0.6.so.0.0.0