UserSelectQueryBuilder has a named() filter to ensure only named users are returned. Unfortunately, it seems to have a bug. The following code:
var_dump( $this->getServiceContainer()->getUserIdentityLookup() ->newSelectQueryBuilder() ->named() ->fetchUserNames() );
returns the following on my system:
[...] string(14) "147.32.219.118" [57]=> string(10) "172.19.0.1" [58]=> string(10) "172.26.0.1" [59]=> string(11) "192.168.0.1" [...]
Those actors are certainly not named, but they are indeed not temporary.