What’s the color function for ComplexPlot’s “CyclicArg”?

I’m having trouble finding the color function in Mathematica (12.3) mapping arg(f) to “CyclicArg” in ComplexPlot. ColorData("ThemeGradients") lists “MidShiftBalancedHue”, which is the unshaded version.

What dark to light shading parameters does CyclicArg apply to ComplexPlot(z, {z, 1}, ColorFunction -> None) to make it ComplexPlot(z, {z, 1}, ColorFunction -> "CyclicArg")?

Note: the number of contour lines (12 in the above example) seems to have no bearing on shading effects applied between contour lines — I’d like to understand the latter.