The UDP config and code was overhauled in 1.22, various methods and config variables were deprecated.
As part of this, I've proposed https://gerrit.wikimedia.org/r/#/c/92455 to update the mediawiki config for WMF
RecentChange::sendToUDP() is marked as deprecated, but no direct hint as to what it should be using.
Version: master
Severity: minor
Change 92461 had a related patch set uploaded by Reedy:
Update CentralAuth recent change notification code
Change 92463 had a related patch set uploaded by Reedy:
Update CentralAuth RC2UDP config
Change 92461 merged by jenkins-bot:
Update CentralAuth recent change notification code
Change 117667 had a related patch set uploaded by Reedy:
Remove remnants of old CA RC2UDP config
All three patches were merged a while ago - is there more work left to do here (if yes: please reset the bug report status to NEW or ASSIGNED), or can you close this ticket as RESOLVED FIXED?