Gigapixel AI introducing large partially transparent splotches onto solid black .png sections


I’ve tried every way I know of to increase the resolution of my black transparent png files. It does it on any black png I try it on. It replaces huge sections of the solid black with partially transparent splotches, when the transparency should only be on the outside. This is even at 2x res increase.

Is there any workaround or recommendations I can try? I’ve considered adding a white background to the image before increasing its resolution, then removing the white background after, but I’m afraid that will be harder than it looks because the ai may introduce other background colors than white upon upscaling.