Mismatch between observed BP/RP spectra of 18 solar twins from Galarza et al. (2021) with A₀ <  0.001 mag (black lines and grey contours) and model BP/RP spectra from PHOENIX (orange lines), MARCS (red lines), CALSPEC sun_model_001 (blue lines), and 3D Stagger (yellow lines). Panel (a): all BP spectra scaled to G = 15. Panel (b): same as panel (a) but for RP. Panel (c): differences from median observed BP spectrum in panel (a). Panel (d): same as panel (c) but for RP. Grey contours in panels (c) and (d) indicate the pixel-wise central 68%, 90%, and min/max intervals given the 18 solar twins.