katello pulp url setting in katello.yaml is no longer set by the installer and the default uses localhost rather than FQDN
As it turns out, Katello wasn't ready for this to be removed: https://github.com/theforeman/puppet-katello/commit/aa27779c4bf46442d5a5543c54e593798ce580af#diff-510884a7414666a0d988133c5f869510210d883aa1580d1248e74f1d16ca7d91L34
The default is no good any more and people see localhost for their repos' "Published At" url. Default: https://github.com/Katello/katello/blob/master/lib/katello/engine.rb#L40
This issue was brought up in a community thread: https://community.theforeman.org/t/katello-4-0-all-repos-are-localhost/23201
We need to change the default to use the machine's FQDN.