How can I reproduce this? I've taken two screenshots of the search overlay, but I see descriptions only in beta.

Stable:

Beta:

I also didn't see descriptions in watchlist (neither in stable, nor in beta).

I'm seeing this in beta labs currently and it's causing browser test failures

Talking to JK he is quite happy with this accident but advises adding a kill switch and fixing browser tests.

(It will reach enwiki on Thursday)

JK: In my opinion, given the status of T101719, this is what we want just bit earlier than expected..

Change 249579 had a related patch set uploaded (by Jdlrobson):
Wikidata descriptions should only be displayed in beta

https://gerrit.wikimedia.org/r/249579

Change 249585 had a related patch set uploaded (by Jdlrobson):
Wikidata descriptions should only be displayed in beta

https://gerrit.wikimedia.org/r/249585

Change 249585 abandoned by Jdlrobson:
Wikidata descriptions should only be displayed in beta

https://gerrit.wikimedia.org/r/249585

Change 249579 merged by jenkins-bot:
Wikidata descriptions should only be displayed in beta

https://gerrit.wikimedia.org/r/249579

Change 249585 restored by Jdlrobson:
Wikidata descriptions should only be displayed in beta

https://gerrit.wikimedia.org/r/249585

Change 249585 had a related patch set uploaded (by EBernhardson):
Wikidata descriptions should only be displayed in beta

https://gerrit.wikimedia.org/r/249585

Change 249585 merged by jenkins-bot:
Wikidata descriptions should only be displayed in beta

https://gerrit.wikimedia.org/r/249585

@Jdlrobson has implemented the required kill switch mentioned in the ^ ticket, so we are all set here.