/usr/lib/x86_64-linux-gnu/libsidplayfp.so is in libsidplayfp-dev 1.2.2-1.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/lib/x86_64-linux-gnu/libsidplayfp.so.3.0.7
/usr/lib/x86_64-linux-gnu/libsidplayfp.so.3.0.7