Update from PHP 5 to PHP 7.0 - PHPmyAdmin will show two server logins: localhost / localhost:3306
There are two ways to connect to the mysql on the localhost. One is the connection via network @localhost:3306 and another is the connection through the filesocket like /tmp/mysql.sock. Filesocket connection is preferred due to the lower overhead and mysql library choose it if available when connection to the localhost requested. I have no clue why they are separated now.

If you want to connect to the mysql only locally then networking can be disabled completely in the my.cnf so all connections are forced to be filesocket-based. That is also a bit more secure as far as no one can connect to the mysql over the network.