If you have more than a couple of users, or users using different workstations, it is a good idea to disable the user list. The below method has been tested on RedHat 8.
Create the file /etc/dconf/profile/gdm
and add the following to it:
user-db:user
system-db:gdm
file-db:/usr/share/gdm/greeter-dconf-defaults
Then create /etc/dconf/profile/gdm
containing:
/etc/dconf/profile/gdm # Do not show the user list
disable-user-list=true
and activate it all by running dconf update
.