Multi color prints wall thickness

I have been trying to understand why I have inconsistencies where I can see one filament under another. The right side is acceptable but you can see an underlying layer on the left side is too extreme.

In the settings, all I have is walls set to 12 to avoid infill, and ironing is turned on. I set walls high because it is a thin object and I don’t want to see infill. I have modified the model to make it thicker but I can still see though.
I can see inconsistencies in the preview but it doesn’t explain the final print.
48 lines total.

I have painted the top geo blue. I tried it a few times to see if I got a different preview, but it is the same.

I have seen this issue before where one filament bleeds into another area that was specifically painted a different color. That was in infill, but this is just walls.

Any ideas how to avoid the shadow effect from the underlying grey filament?