The $validate operation (http://hl7.org/implement/standards/fhir/operation-resource-validate.html) list the profile parameter as an uri type. The Meta (https://www.hl7.org/fhir/resource.html#Meta) lists profile as a canonical.

The $validate operation should actually take a canonical as parameter - how else would you state the specific version of the profile.

Discussion from https://chat.fhir.org/#narrow/stream/179166-implementers/topic/bug.20in.20spec