The .disabled class uses pointer-events:

The .disabled class uses pointer-events: none to try to disable the link functionality of <a>s, but that CSS property is not yet standardized. In addition, even in browsers that do support pointer-events: none, keyboard navigation remains unaffected, meaning that sighted keyboard users and users of assistive technologies will still be able to activate these links. So to be safe, in addition to aria-disabled="true", also include a tabindex="-1" attribute on these links to prevent them from receiving keyboard focus, and use custom JavaScript to disable their functionality altogether.