Good observation. I took a look at the texture file, I'll explain why it looks grey from a color theory perspective and why it stands out, otherwise take it all with a grain of salt. It's why
Colors appear relative to what it is surrounded by, you're seeing this 'greyish' line despite it actually not being anywhere grey because it's surrounded by colors of slightly higher saturation making it look duller/muted/grey. Normally such color difference wouldn't be a 'huge' issue but the second issue is that the 'grey' area is just really harsh desaturated line causing it to stand out. I did a scuffed swatch for you to inspect if you want. [
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I personally never noticed it until you pointed it out and even then I found a hard time seeing it, but I think it's more an issue with my eyes ahaha
Really odd honestly, I wonder why it exists, is this some imperfection generated by an upscaling software or AI...?
I think they might've missed it, I had to zoom into 800%-1200% to actually be like 'ohhhhh', I hope it gets fixed, along with the eyelid issue but I doubt it unless someone points it out.