Fade rendering mode showing a marquee around transparent texture

Hi.

I have this image with transparent background.

I want to add it in the intersection between wall and floor, to add a dirty look. But as you can see, there's a kind of black line at the top limit of the plane that shows the texture. Like a marquee

The rendering mode is set to Fade because Cutout despite correcting this marquee thing, just oversimplifies the image in a way I don't like. Anyone knows how to solve this?