Found this on the Capture One site:
The ProStandard profiles are available starting from Capture One 21 (14.0.0). They are particularly suitable for portrait photography and product photography of the objects with saturated or very bright colors.
The ProStandard profiles render colors more naturally, so there is a better transition between the hues and better retention of colors after the adjustments have been applied. Overall, the colors look natural from shadows to highlights with the ProStandard profiles.