By default Debian will enable services (and start them) after
installation. This is a problem for templates, which is why there is
specific advice about installing services in to Debian templates.
By contrast Fedora does not automatically start services.
There are many services which can be enabled or disabled in an template
based qube. cups is just one of them.
That said, I'm puzzled as to why cups *is* running in your template - it
doesn't seem to be in my Debian 10.