This usually happens because you have changed the color with the WordPress editor. If you change the color from here, then any color changes in the “styling” tab will not apply to your text. The best practice would be to use only the styles from the styling tab. Use the WordPress editor only when you want more text colors/sizes in the same paragraph and don’t want that text to be responsive.
Delete the style colors you see here, and then the colors from the styling will apply.