All MediaWiki version pages (e.g. MediaWiki 1.38) currently show "This page contains release notes for a version of MediaWiki." regardless of their support status.
In fact, on source document pages, {{#invoke:Template translation|getLanguageSubpage}}
would always return "en", so the second parameter would always be used, but never the first one, regardless of whether one is on a source document page or a translation subpage.
Please try to fix this problem as soon as possible.