Tentatively planned based on the timeline of the security readiness review of the Json Patch PHP library. (T316523)
PATCH method should not be available in the Wikibase REST API.
API specification and the autodocs should not mention unavailable routes.
Likely means moving the PATCH routes to a separate files so that routes.json will only contain routes that can be used in production environments, including WMF production environments. (Wikidata)