A developer needs to update the rating on a specific color in a Redux reducer. They write:

case 'RATE_COLOR':
  return colors.map(color => {
    if (color.id === action.id) {
      color.rating = action.rating
    }
    return color
  })

The ColorList component re-renders (the array reference changed), but the matched color's displayed rating doesn't update. What is wrong and what is the correct fix?