/usr/lib/x86_64-linux-gnu/libzstd.so is in libzstd-dev 1.3.3+dfsg-2ubuntu1.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/lib/x86_64-linux-gnu/libzstd.so.1.3.3
/usr/lib/x86_64-linux-gnu/libzstd.so.1.3.3