Radial surface brightness profiles of comet C/2025 D1 on (a) 2 February 2022 from CFHT and (b) 30 May 2022 from HSC. These images have higher S/N for the comet than any other observations we collected. The azimuthally averaged surface brightness is plotted in olive green. The best-fit radial surface brightness model is shown as a dashed red line, with the derived logarithmic surface brightness slope indicated in the lower left corner. The boundaries of the fitted region are marked by the two vertical dashed blue lines.