The Rp template exists on various wikis (Wikidata item), to put a page number next to an inserted reference. Given local rules, this question doesn't concern all wikis. For instance, frwiki is affected, enwiki isn't.
In the treatment of error 67, WPCleaner should consider the ref tag and the Rp following template as a single entity, in order to change (or suggest) bla.<ref .../>{{rp|n}} into bla<ref .../>{{rp|n}}. rather than bla<ref .../>.{{rp|n}} .

Related task T256312