We've discussed this in the design team back when we've brought the color palette to OOUI, see T146823 and alike. We've decided, backed by WCAG 2.1

Incidental: Text or images of text that are part of an inactive user interface component, that are pure decoration, that are not visible to anyone, or that are part of a picture that contains significant other visual content, have no contrast requirement.

not to increase color contrast on a number of disabled elements, where readability could be neglected. In contrast see our weighed in fulfillment of contrast ratios on labels for disabled elements or inactive tabs.
Context decides and product designer has to provide sufficient contextual information to make user clear about how to enable element if possible and what it is about.

Yes, indeed, that unfortunate exception :-/

I guess the standard is the standard, and we're therefore not obliged to make a visual change here, but I completely agree with your last sentence: it's still very important that we help individuals understand that something is unavailable or not ready to be used and why, to make sure the same information is available to users regardless of their vision.

Thanks @Sarai-WMDE! Captured in https://github.com/wikimedia/WikimediaUI-Style-Guide/pull/462 for further clarification.

Oh! Nice move. Thanks for adding that note, Volker 🙏🏻