Don’t know whether I should report this as a bug, because I’m not sure if this is a problem with ROBLOX, or just how the image is. When I try to upload a decal that clearly has a transparent background, it appears in-game with a black background instead. I’ve noticed that this doesn’t happen with any of my other decals, only this one.
The original image.
How the image looks on a GUI.
How the image looks as a decal.
Transparent Background On Image Appears Black In-Game
Iogician
#1
PeteyK473
#2
This is related to this related to this bug, your image has 8-bit depth:
A temporary workaround is to export the image as 24-bit or 32-bit depth.