The Google Things To Know box, which was announced at Google I/O, and eventually has been showing up for about 1% of desktop queries, is no longer showing up for any desktop query now, according to RankRanger data. Google began showing the things to know box more often last March.
In any event, RankRanger shows it dropped off completely now on Google desktop search:
Shay Harel from RankRanger confirmed this on Twitter saying "Things To Know was removed a few days ago from desktop, my guess is the live test was not as expected and it being refined. Things To Know on mobile is still alive and pretty stable on ~1%."
So maybe it was a bug, is a bug or something else.
Hat tip @SEO_Suedwest for spotting this earlier.
Forum discussion at Twitter.