/usr/lib/x86_64-linux-gnu/libnvtt.so is in libnvtt-dev 2.0.8-1+dfsg-8.1.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/lib/x86_64-linux-gnu/libnvtt.so.2
/usr/lib/x86_64-linux-gnu/libnvtt.so.2