Recreate PostProcessing v1 Color Grading saturation artifact (banding) in v2

When I upgraded to PostProcessing v2, the banding effect I was seeing at high saturations under v1 disappeared. I totally get why this effect would be seen as something to be corrected, but I actually liked it and haven't been able to recreate it under v2. I'm considering writing a custom effect to do so but I'm not actually sure what technically I'm trying to recreate. Any pointers appreciated!

Here's the effect, which appears as I increase color grading saturation (shown here at a value of 2)



Here's the same scene with saturation set to 1:



Thanks...