It's showing up weird in the specs tool and when I look at it in my programs. Your source file might have it right, but it might be getting wonky when you export it. Try converting it to indexed mode before you save as PNG, to make sure the palette is preserved.
It looks like sometihng got wonky when you exported this image, there are a bunch of colours that are almost identical. For example, the little heart looks solid, but is made of 5 different colours.
Oh, i find it! ur right! But indexed mode will lost white color, #FFFFFF will be come to transparent, i usually not use this mode.