User blog comment:MisterWoodhouse/Fandom is upgrading to a modern version of MediaWiki/@comment-38722340-20190626064354/@comment-1038387-20190626110442

... that's not the evolution.

Wikicities/Wikia/Fandom powered by Wikia/FANDOM/Fandom always used MediaWiki. Now, they're just going from a heavily forked 1.19 to something newer. Current stable release is 1.32.2, but they might go to a slightly older version.