This MCC Profile  https://build.fhir.org/ig/HL7/fhir-us-mcc/branches/master/StructureDefinition-MCCClinicalTestObservation.html derives from US Core 5.0.1 Observation Clinical Test Result Profile.

Depending on the outcome of the US Core January ballot reconciliation with respect to the “lumping” of the various observation profiles, the MCC IG will determine which of the US Core 6.0.0 profiles that the MCC IG will “lump” its profiles to for its STU ballot in September, while keeping its current design for this January "Comment Only" ballot given that the MCC dependency is on US Core 5.0.1 and knowing the US Core design may flux during  the 6.0.0 ballot.

MCC will respond accordingly