User Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.14; rv:68.0) Gecko/20100101 Firefox/68.0

Steps to reproduce:

1. Open a web page that includes a disabled button using Firefox
2. Open Firefox Devtools
3. Switch to Accessibility panel and check for contrast issues

Actual results:

The disabled button is listed for its low color contrast issue

Expected results:

The disabled button should be skipped when checking color contrasts according to WCAG 2.0.

Related Specs:

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.

From https://www.w3.org/TR/UNDERSTANDING-WCAG20/visual-audio-contrast-contrast.html