Vector appears missing some styles. This results in the category bar being displayed, even when it does not make sense (https://www.mediawiki.org/wiki/Special:RecentChanges), the category bar missing its styling when there are categories (https://www.mediawiki.org/wiki/Skin:Femiwiki), the printfooter (Retrieved from) being visible unconditionally and Special:Version missing the table styling.
This only occurs on group 0 wikis, like the aforelinked pages on mediawiki.org.