/usr/lib/x86_64-linux-gnu/libnss_mysql.so.2 is in libnss-mysql-bg 1.5-4build1.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/lib/x86_64-linux-gnu/libnss_mysql.so.2.0.0
/usr/lib/x86_64-linux-gnu/libnss_mysql.so.2.0.0