It is because the texture of that keycap is the same than the other keycaps. That keycap does not have clickclack's signature (perfection) on it
I can tell from some of the pixels, and from seeing quite a few shops in my time.
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C'mon, it was the perfect opportunity to you that line! They even have pre-made images of it, if you're into that sort of thing (I'm not, I prefer to type things out)
Also, the lighting's off. Check where the light shines and the shadow reflects. It doesn't match up with the vader, like the rest of the keys, While this is still possible to do in real life, it's also much more likely to occur if one is stitching together two different pictures.