Is there definitely no soft edge on the sprite itself? Maybe your art program has a setting to premultiply the alpha or not? Make sure your program is saving the transparent pixels as black, i.e. RGBA 0,0,0,0.
Sry for the late reply. I see what you mean, I did soften the edges a bit in Clip Studio, but I’m not sure I want to get rid of that softness. Is there maybe another way around it?