(Nice, I mention this in https://www.mediawiki.org/wiki/API:Presenting_Wikidata_knowledge#See_also )
The wbgetentities API call returns
... "ar": {"language":"ar","value":"\u0644\u063a\u0629 \u0625\u0646\u062c\u0644\u064a\u0632\u064a\u0629"}, etc.
Assuming all JavaScript clients can handle UTF-8, specifying formatversion=2 or utf8= in the API request returns:
... "ar":{"language":"ar","value":"لغة إنجليزية"}, etc.
The response is approximately 20% more compact for the qLabel main page example.