I would like to see a drastic drop in saturation. It feels like PowerPuff Girl's UI. So tiering for my eyes.
I don't care for customization of the UI just to have the option at least to drop saturation on those Icons and remove the pure white dominating elements so that my eyes don't get tired so easily when in Light Mode.
Would be interesting if icons support two variations in iOS 15, one for Light Mode and one for Dark Mode.