After a clean install of XAMPP 5.6.33, I see a user in phpMyAdmin called User name: 'Any' @ localhost. It's listed in red with the following warning:
A user account allowing any user from localhost to connect is present. This will prevent other users from connecting if the host part of their account allows a connection from any (%) host.
Indeed I am unable to login as a user with % hostname. If I delete this 'Any' user, then everything seems to be fine. My question is why does this blank user get created by default? It's both a security risk and an inconvenience.
There is also a user 'Any' at %, which doesn't seem to cause a problem, because it has privileges only on test databases.
I am running macOS 10.13.4.