A success and an error differ only in the icon's shape and color, and the icon is hidden from screen readers. A reader who cannot see it, or cannot tell green from red, gets the outcome from the words.
- Say the outcome in the title. “We could not save your changes” works when read alone. “Changes” over a red circle does not.
- status colors the icon and nothing else, so it cannot make a neutral sentence read as a failure.
- If your icon carries meaning the text cannot, give it an aria-label, which gives the Icon role="img".