More work on getting the Wikibase Quality extensions ready for deployment. They'll improve constraint checking and provide checks against 3rd party databases.
Special:UnconnectedPages had to be reworked (thanks Amir!) because of huge performance issues. Because of this it loses some functionality (being able to specify where the list starts and limiting the list to pages that have local interwiki links). We're working on bringing functionality back without the performance penalty.
Enabled arbitrary access on arwiki, cawiki, eswiki, huwiki, kowiki, rowiki, ukwiki, viwiki, and usage tracking on dewiki, ruwiki, cswiki and all s3 wikis. (ruwiki and cswiki get arbitrary access on June 23)
Finishing work on improved handling “invalid” values and statements with deleted properties.
Small breaking DOM change: Wikibase no longer adds its own h1 tag but uses MediaWiki's default .firstHeading element. (phabricator:T93534)
More work on getting the Wikibase Quality extensions ready for release. The part doing constraint violation checks should go to test.wikidata.org next week. The part doing checks against 3rd party databases will still take a bit longer but is also shaping up nicely.
Made it possible to create items even when another user is mass-creating items (phabricator:T103796)
Bene* worked more on making Wikidata work nicely on mobile