/usr/lib/x86_64-linux-gnu/libmbedtls.so is in libmbedtls-dev 2.2.1-2.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/lib/x86_64-linux-gnu/libmbedtls.so.10
/usr/lib/x86_64-linux-gnu/libmbedtls.so.10