When viewing the rest api online docs, swagger tries to call out to:
https://online.swagger.io/validator?url=https://www.mediawiki.org/api/rest_v1/?spec
This call is blocked by CSP. If it went through, this would probably be a violation of the privacy policy. Well its good its getting blocked, CSP should be a check of last resort. The Rest API stuff should not serve things that instruct the browser to fetch external resources.