A watermark covers part of the frame, and removing it cleanly is harder than it looks: there are no original pixels underneath, so something has to replace them. An eraser or clone stamp in an editor takes its patch from a neighbouring area, which is why they only cope on flat backgrounds — on grass, fabric or a pattern the seam stays visible.
The Grom Art model rebuilds the background under the mark from the meaning of the whole frame instead of copying the piece next to it. All it needs from you is the file and a two-word prompt — no mask required.





