I believe this is a nude filter of an uncropped version of post #7691.
Flag justification: The usual telltale signs are there, mostly unevenly redrawn lines, besides the low-quality crotch redraws. As the details are pretty hard to spot, I have marked them with notes. Unfortunately, I was unable to find the original image this shop was based on. The closest I could find was a wallpaper over at Sankaku. The curious viewer may place a downscaled version of the Sankaku post over this one in an image editor to make spotting the differences easier.
Uneven line thickness where the panties were removed.Uneven line where the seam of the panties was removed.Unevenly redrawn outline with two dark spots where the panties’ seams were removed.Uneven line sharpness and coloring where the panties’ frills were removed.Pixellated artifacting on the hair strand and uneven body outline where the panties’ frills were removed.Teal hue from the panties remaining in an otherwise completely skin-colored area.A crease of the panties remains between the butt cheeks.Note that this circle (and a few other details) is only visible in the shirtless sibling post #7691 and not in the parent and sibling posts with shirts. This indicates that the shirtless version (with panties) was a later revision done by the original artist.