Aside from the clothing filter being wonky, it may be the messy erasing job on the shirt portion. I suggest using paint dot net (paint.net just goes to some random paint website; just search the download) to design, and use multiple layers so that you can easily get rid of whatever.
Roblox’s filter could have flagged the little specks on the upper portion as some sort of… inappropriate shirt? Or an attempt to make one? No clue. Try being a little cleaner with your erasing/designing whatnot and they should be okay