/usr/lib/x86_64-linux-gnu/libx265.so is in libx265-dev 2.1-2+b2.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/lib/x86_64-linux-gnu/libx265.so.95
/usr/lib/x86_64-linux-gnu/libx265.so.95