We zoom on the detection location in J0946+1006 and show the residuals between the model and the data for all considered variations of subhalo properties. In each panel, the dashed blue line shows the critical curve predicted by the model, and the black contours trace the surface brightness of the arc. In the first panel, we see a clear red spot at the edge of the lensed arc, which is close to the detection location and indicates that the smooth model cannot correctly reproduce the surface brightness distribution. The NFW models with fixed concentration (second panel) and position (third panel) cannot remove this excess, while the residuals reach the noise level when the NFW is allowed to have a higher concentration (fourth panel) or when we use a PJ or PL profile (last two panels).