/lib/x86_64-linux-gnu/libreadline.so.5 is in libreadline5 5.2+dfsg-3+b1.
This file is owned by root:root, with mode 0o777.
It is a symlink to /lib/x86_64-linux-gnu/libreadline.so.5.2
/lib/x86_64-linux-gnu/libreadline.so.5.2