I'm not sure I've ever seen an "upscale" of any kind of heavily pixelized art to something much higher resolution that doesn't seem similar in quality. There seems to be something fundamental to the pixelized aesthetic that once you try to upscale it just can't be the same and human brains will never read the very upscaled art as "yeah, the same, just depixelized". I've seen plenty of 100% human attempts at this and they all seem to have the same subjective effect to me.
People must just be pickier than me. I see this comment on everything AI from the worst to the best.
I took a glance through and everything looks perfectly fine to me.