Wide open, virtually every lens shows uncorrected aberrations off-center; point are not rendered as points. Aberrations are discussed in detail in Making Sharp Images.
The 85/1.4G shows typical “point with triangle” rendition off-center. This is a combination of aberrations, with no simple explanation, but is very common with 50mm f/1.4 and 85mm f/1.4 lenses. Stopping down to f/4 is required to render points as points, with f/5.6 bringing very pretty diffraction star patterns. Axial chromatic aberration which manifests as violet (purple) fringing is also present with the 85/1.4G (and virtually every f/1.4 and f/2 lens).
Click to view a larger images, and a variety of crops which show the aberrations.
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