Check these posts by DxO staff member @Benoit (Aug 2018): https://forum.dxo.com/t/dpl-and-lens-diffraction/4463/5
and three posts later:
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Consequently, as diffraction contributes more and more to lens sharpness when aperture decreases, its effect is taken into account in our dxo modules, and thus lens sharpness tool has an impact on it.
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and
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As lens sharpness correction already includes the action on diffraction, and as it would be quite costly to split in each DxO modules the part of the blur caused by diffraction, we don’t think about such a feature for the short term.
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