I shot these images with my Sigma 24–70 and Sony A7iii, in fog, sometimes pointed into the "sun" (it was not actually sunny but sometimes the lens was pointed towards the direction of the sun). I believe they were shot at above 1/1000th of second. I have front e-shutter disabled.
I've only ever seen this happen with Sigma lenses (24–70 and 85) on my A7iii, not other brands. I'm not saying it's not possible, just that I've never noticed it. It seems to happen regardless of the lens hood being attached or not.
I'm wondering why there is a darker shadow on the left side of the frame with a semi-circle/halo-like pattern there.