/usr/lib/x86_64-linux-gnu/libzephyr.so is in libzephyr-dev 3.1.2-1build2.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/lib/x86_64-linux-gnu/libzephyr.so.4.0.0
/usr/lib/x86_64-linux-gnu/libzephyr.so.4.0.0