/usr/lib/x86_64-linux-gnu/libde265.so is in libde265-dev 1.0.2-2+b2.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/lib/x86_64-linux-gnu/libde265.so.0.0.10
/usr/lib/x86_64-linux-gnu/libde265.so.0.0.10