It's because of @matmarex's patch on T245794 to turn it on as a beta feature on the beta cluster -- because of how T245539 implemented the beta-feature stuff, if it's in beta-features it hides unless the specific enabled-for-beta preference is set.

Yes, this is expected, we wanted to have the same configuration on the beta cluster as on production wikis (although that deployment is now postponed).

You can either enable the beta feature in your preferences, or use the old ?dtenable=1 parameter if you want to test without a account.

Well, since we now have tested it on the beta cluster, and it works as expected, perhaps we could turn it back on for everyone on beta cluster only? @Jdforrester-WMF Is that okay by you?

Sure.

Change 580383 had a related patch set uploaded (by Bartosz Dziewoński; owner: Bartosz Dziewoński):
[operations/mediawiki-config@master] Re-enable DiscussionTools for everyone on the Beta Cluster

https://gerrit.wikimedia.org/r/580383

Change 580383 merged by jenkins-bot:
[operations/mediawiki-config@master] Re-enable DiscussionTools for everyone on the Beta Cluster

https://gerrit.wikimedia.org/r/580383