Originally discussed by @1Copenut and @cee-chen in #6630 (comment)

I think we need to take the time later to evaluate our placeholder text color contrast across the board / across all form/input elements, not just this one. IIRC WCAG allows lower contrast ratios for disabled elements... but apparently not for placeholder text (https://www.w3.org/WAI/WCAG21/Understanding/contrast-minimum.html) 😕

Unfortunately, our current form/input component native placeholder text and our components that mock pseudo placeholder text (EuiComboBox, EuiSuperSelect) likely do not meet color contrast minimums. We should address this across the board in all components with placeholder text if possible.