I would assume that its about the unsharp Details in those pictures. De Chip does not have much Details and also the Bowtie have unsharp areas.
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Are these AI generated Illustrations? They appear to be. I wonder what the reason is for upscaling through Gigapixel?
At first glace the cutout work on the bow tie needs some work to smooth it out a bit in places, and both the computer chip and motherboard images have an odd overprocessed appearance in the details when zoomed in. This is very common with AI generated content, but it could also be from Gigapxel.
I doubt its the cutout work though. I do that part manually, not a background remover, which I find dont do a great job. I might have been under the impression that Gigapixel AI improved quality, rather than just enlarging the photo...still not sure.
The cutout work on the bow tie is good, but it does have some noticeable imperfections. For a commercial asset, Adobe is looking for assets free of any technical imperfections in my experience.
Are these AI generated illustrations? That could also be the reason for the overprocessed look in the computer chip and motherboard images.
It was just the standard reason/no-reason of quality issues.
So I don't know enough (outside of the guidelines given on the sites supporting documents) about the factors of quality to know which would be the issue.