User blog comment:MisterWoodhouse/The first migrations to the Unified Community Platform/@comment-24544305-20200814223123/@comment-3999290-20200815134216

Just try to understand that WikiActivity is not a standard MediaWiki feature, and so it was not removed simply because it doesn't exist in standard basecode.

WikiActivity was developped by Fandom in the highly customized basecode runing on legacy platform. Wikis running on the new basecode can't get it, just because the feature must be developped, but it can't be ported easily. Maybe WikiActivity will be back later, but don't expect it will be designed like it is on legacy.