Seriously, what's going on here. It's like someone completely failed to properly align their stitches.
The issue exists in all the other pictures from the same gallery on exhentai too. They're all from the digital release of the doujin here: https://www.dlsite.com/maniax/work/=/product_id/RJ246530.html so the artist might have just screwed up this release since the original pixiv uploads don't have the problem.