Dark mode is broken on vector legacy

Not sure when this started (I haven't accessed the wiki since a few weeks), but the dark mode is broken on the Vector legacy skin :

https://wiki.archlinux.org/title/Main_page?useskin=vector
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Interestingly, this issue happens:

  1. Only when logged in
  2. On all pages, except preferences

Looking at the dev tools, this seems to be caused by a buggy CSS declaration for html.client-darkmode:
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If I disable this declaration (or remove the client-darkmode class on the <html> element), this fixes the issue.

I don't have any custom CSS/JS:
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(I've since this screenshot added a custom JS to temporarily remove the client-darkmode class as a workaround, but I guarantee that I had none before)

I'm on Chrome 135.0.7049.84 (official Google build, not the chromium bundled in the repos). I reproduce the issue by logging in to the wiki in incognito mode, so this isn't caused by any browser extension.