/usr/lib/x86_64-linux-gnu/libopenslide.so is in libopenslide-dev 3.4.0-1+b3.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/lib/x86_64-linux-gnu/libopenslide.so.0.4.0
/usr/lib/x86_64-linux-gnu/libopenslide.so.0.4.0