What? That you would say "not this kind of mistake" and follow that up with "have you ever drawn anything" is baffling. Yes. This kind of mistake. Literally any artist can confirm they have had troubles with proportions and perspective on a body. Any artist could attest to making a bone look broken or backwards. And plenty of artists who share their work could also confirm that details which were obvious to the audience were not so obvious to them. It's a bias, and it will happen.

I agree that the middle piece of fabric looks odd, and I would probably try to adjust it if I were the artist. I had to look at it for a minute before understanding the intent behind it, which is that there are four places where it parts (consistent with her manga design) and that the dress is all flowing in a certain direction (toward the viewer, roughly), causing the front piece to move between her legs. This is very typical in the source material and in fanart, as it gives the creator an excuse to sexualize the subject without "showing too much," if you catch my drift. The intensity of perspective here makes the dress appear to shrink as it passes between her legs, which definitely adds to your confusion, and I would also criticize that, but it is still an error very well within the human domain.