Wikidata was readonly from 5:48 to 7:04 on 2017-07-28. Per T171928#3480528, there're many deletions and moves made in this period. They should be cleaned up. Unfortunely Hoo Bot is not running since 2016-10-12.
Before T143486: [feature request] remove sitelinks / update sitelinks on Wikidata when pages are deleted/moved on client wikis (all users) getting fixed, we probably need to run it periodically.