Whenever an element is an AJAX trigger,
Drupal.Ajax.prototype.beforeSend applies the
disabled HTML attribute to it.
This may prove to be troublesome for some keyboard users in certain form configurations, as these elements become non-interactive.
Might it be more appropriate to apply
aria-disabled here instead and to prevent value changes in another way?
It affects the ability of people with disabilities or special needs (such as blindness or color-blindness) to use Drupal.