In the Understanding to 1.4.1, erroneous fields or required fields that are only color-coded are given as examples of violations of 1.4.1.
What about the disabled and readonly states when they are only transmitted in color. Is that ok or a violation of 1.4.1 (if contrast difference to operable elements is less than 3:1)?
I think that the difference between disabled and operable meets 2 of the 4 criteria in SC 1.4.1.:
- conveying information
- prompting a response
However, this seems to be controversial and that is why I would seek clarification. @alastc (#1781 (comment)) wrote e.g.
I'm not convinced that WCAG requires you to differentiate a disabled button visually.