Hmm, that image doesn’t appear to be transparent at all. If I open it in Ps, and put a layer behind it, the layer doesn’t show through at all. It appears to be a solid image with gray squares on it.
The only place you need the fading to pure transparency is the bottom. I’d just erase the white from the upper right corner and left side of the mag glass, then gradient a fade-to-100%-transparency for the bottom (so long as the edge of the image is 100% transparent, you won’t see the edge of the image).
Something I’ve run into so many times doing Gaussian blurs on stuff that was already touching or close to the edges… the blur would stop at the edge because there was no room to fade completely, making ugly edges lawlz. Now I know to always extend my canvas before blurring!