>>4206253That's not self-evident, is it? Whether there's a color shift depends on where and how much each layer scatters and reflects, which we can't know. The reflection could also be from higher up like the cover glass.
>>4206323Pic is from an a7iii with Sigma 24-70 at 70/2.8 with a cheap uv. At less than infinity focus the ghost is on a different plane than the light source. It falls off very quickly away from the image center. That probably does have to do with the mount design, since you could think of the sensor-reflected light as being cut off by the exit pupil.
Hmm, looking at the live view some more there are focal lengths where this lens has subtle ghosting even without a filter. It's probably just inevitable that in zooms elements are sometimes positioned so that reflections are in focus.