This came up a while back so I thought I'd mention a workaround.
Background: for no apparent reason, CUPS keeps reporting "Expiring
subscriptions..." to the journal, once per second, forever. Despite
diligent Googling I couldn't find a definitive solution (or indeed
explanation) for this, so I finally reported it to BZ:
https://bugzilla.redhat.com/show_bug.cgi?id=2233078
A proper resolution is hopefully around the corner, but in the meantime
the BZ thread mentions a workaround which did solve it for me, at least
temporarily.
poc