on https://playbook.cio.gov/designstandards/form-controls/ the accessibility guidelines state :
"If you adjust the color scheme of the buttons, ensure a minimum contrast ratio of 4.5:1 (for small text, 3:1 for large) for all states of the button. This includes default, hover, selected, and disabled."
WCAG 2.0 doesn't require minimum contrast ratio for disabled interface component because otherwise user can't know it's disabled cf : WCAG 2.0 1.4.3 criteria "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."
on https://playbook.cio.gov/designstandards/form-controls/ the accessibility guidelines state :
"If you adjust the color scheme of the buttons, ensure a minimum contrast ratio of 4.5:1 (for small text, 3:1 for large) for all states of the button. This includes default, hover, selected, and disabled."
WCAG 2.0 doesn't require minimum contrast ratio for disabled interface component because otherwise user can't know it's disabled cf : WCAG 2.0 1.4.3 criteria "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."