See T183869: Collect AICaptcha data from WikimediaEvents extension and m:Research:Spambot detection via registration page behavior for context, and T183991: UI for notifying users about data collection for the UI. Plan is to deploy to group1 on Monday and group2 on Tuesday. The first step involves backporting MediaWiki-extensions-WikimediaEvents and MediaWiki-extensions-Campaigns patches to the active WMF branch; the second is just a config change.
Adding Performance-Team for visibility. The patch pulls in OOUI core for the popup widget, which adds ~50K (after gzip) Javascript to the registration page, which means almost doubling the size of the page. (This is done on desktop only.) Assuming this is not a big deal since it has to be done sooner or later anyway due to T85853.
Monitoring is tracked in T185870. The logging code is planned to be live for about a month.
Was disabled in 2018 September and undeployed in 2019 January.