Steps to replicate the issue (include links if applicable):

• Open Special:Randompage on German Wikipedia in any desktop skin.
• Look at any encyclopedic article in German environment.

What happens?:
Tab text for this article is Seite (=page; the generic name for all unidentified pages).

• Same on any related talk page.

What should have happened instead?:
Tab text for backlink to this article is Artikel – especially needed if any derived action= rather than view is requested, and the view mode shall be displayed, or to navigate from talk page to article.

Software version
Current MW.

Other information

• While MediaWiki:nstab-main is set to the legend specific for main namespace within a Wikipedia, this is ignored here. WHY?
• If appending uselang=qqx to URL the tab text pretends: (nstab-main) – fine.
• On other namespaces, like Help: or Template: or Category: or Project: or Module: the label is specific to the namespace.
• The problem was observed first in June 2024; it worked as supposed over decades.

No JavaScript did modify the text, the server response says already:

<li id="ca-nstab-main">
<a href="/wiki/..."><span>Seite</span></a>
</li>