:3

I believe this is an upscaled image... I know it when I see one (obsessed with best upscale), My upscale are even better than this (I believe this was upscaled using UpRGB model since CUNET model (the one I use and also the best) doesn't make it into Waifu2x-caffe last year).
For comparison : https://imgur.com/a/7O2ZzFC
Not that noticeable unless you pixel peep.

The lines indeed look upscaled