On Thursday 7/31, we observed a sudden drop in event produce rate for Reader Growth's LoggedOutRetentionVisit experiment:
The above cliff drop coincided with the train cut to group2 wikis at 7/31/25 UTC 19:32 - https://phabricator.wikimedia.org/T396373#11051829
After much head-scratching, we eventually figured out that the patch to update the experiment name had been backported to 1.45.0-wmf.11 but hadn't been merged to master.
The resolution was to backport to 1.45.0-wmf.12 which ended up restoring the event produce rate for that experiment:
https://grafana.wikimedia.org/goto/tv2sCjwHg?orgId=1
Slack thread: https://wikimedia.slack.com/archives/C05ERLBF0E7/p1753993920317559
As a follow up to the restored event data, the data analyst for Reader Growth asked that the experiment end date be extended to 8/31. Captured as a follow up sub-task T401145: Update Reader Growth experiment LoggedOutRetentionVisit end date