Since Foreman 2.1 (thanks to #28070) if the enable-epel parameter is not set, the default kickstart template will still install the epel. This is due to

<% if rhel_compatible && !host_param_false?('enable-epel') -%>
<%= snippet 'epel' -%>
<% end -%>

https://github.com/theforeman/foreman/blob/4ff6f0a1f0b8c6227f91e6b2bcd5c33e00b22a18/app/views/unattended/provisioning_templates/provision/kickstart_default.erb#L278-L280

The problem is, host_param_false?('enable-epel') returns false in case the parameter is not found (the default value, optional second parameter). Then it's negated to true. This change was introduced in the mentioned #28070

In this ticket, we should

1) switch the default value of host_param_false? to true, like suggested in the original PR https://github.com/theforeman/foreman/pull/7110#discussion_r335387999 (the same for host_param_true?)

2) modify the template to use host_param_true?('enable-epel') and stop doing double negation

3) optionally I'd consider seeding this parameter with the default value false, so people would know, they can actually set/override it