/usr/lib/x86_64-linux-gnu/libgnutlsxx.so is in libgnutls-dev 3.4.10-4ubuntu1.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/lib/x86_64-linux-gnu/libgnutlsxx.so.28.1.0
/usr/lib/x86_64-linux-gnu/libgnutlsxx.so.28.1.0