Hi Donald,
Do we know if the concentric circles are placed dead centre of the captured image (before cropping)?
I ask because I am trying to think how or why DxO would apparently use something like that and the most logical idea that comes to mind would be the CA removal, since the amount of that applied would increase axial'ly from the lens (uncropped image) centre.
If the effect isn't image centred, then I'm at a loss too.
Either way, it doesn't really help beyond 'understanding' the precise cause - it doesn't solve the problem and short of using DPP instead of DxO, won't help.
Hope we get to the bottom of it soon,