/usr/lib/x86_64-linux-gnu/libapt-inst.so.1.5 is in libapt-inst1.5 1.0.9.8.4.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/lib/x86_64-linux-gnu/libapt-inst.so.1.5.0
/usr/lib/x86_64-linux-gnu/libapt-inst.so.1.5.0