Noticed earlier today, because some code that had been deprecated since 1.21 was removed and starting causing fatals, that we don't log deprecation notices in production. This has now been fixed.
Please check logstash for `channel:deprecated` and see if anything you are reposinsible for is using hard-deprecated methods and fix them.
Some culprits which have each generated hundreds of messages in the ~5 minutes it's been turned on:
Use of SpecialRecentChangesQuery hook (used in FlaggedRevsUIHooks::modifyRecentChangesQuery) was deprecated in MediaWiki 1.23. [Called from SpecialRecentChanges::runMainQueryHook in /srv/mediawiki/php-1.29.0-wmf.8/includes/specials/SpecialRecentchanges.ph
Use of wfSetupSession was deprecated in MediaWiki 1.27. [Called from CollectionSession::startSession in /srv/mediawiki/php-1.29.0-wmf.8/extensions/Collection/Collection.session.php at line 38]
Use of SpecialWatchlistQuery hook (used in FlaggedRevsUIHooks::modifyChangesListQuery) was deprecated in MediaWiki 1.23. [Called from SpecialWatchlist::runMainQueryHook in /srv/mediawiki/php-1.29.0-wmf.8/includes/specials/SpecialWatchlist.php at line 309]
Use of Revision::getText was deprecated in MediaWiki 1.21. [Called from FlaggedRevision::getRevText in /srv/mediawiki/php-1.29.0-wmf.8/extensions/FlaggedRevs/backend/FlaggedRevision.php at line 480]
Use of SpecialRecentChangesQuery hook (used in FlaggedRevsUIHooks::modifyRecentChangesQuery) was deprecated in MediaWiki 1.23. [Called from SpecialRecentChanges::runMainQueryHook in /srv/mediawiki/php-1.29.0-wmf.9/includes/specials/SpecialRecentchanges.ph