It seems inconsistent that for MedicationRequest and MedicationStatement, the referenced MedicationResource is only returned if requested (via a search _include _parameter), but for PractitionerRole, the Practitioner and Endpoint references must ALWAYS be returned. Why not only return them when the query requests it (via __include parameters)?

General (non-US-Core) clients that submit a search might not be expecting to receive non-PractitionerRole resources in the results (when they don't use _include) – so this could cause confusion.

Consider changing this to simply require the server support the _includes option for Practitioner and Endpoint. This would avoid confusion and work more like the rest of FHIR works (hence no surprised).

If not, then please specify that the result bundle should set entry.search.mode to "include" for those referenced resources so that non-US-Core clients can properly interpret the results.