Input spectrum of the GRB prior to scattering on Galactic dust sheets. The blue error bars indicate the inferred input X-ray signal for the best-fit model grain-properties. For comparison, the expected shape of a power-law decline of the prompt signal (dashed black line) with substantial MW and host galaxy absorption found in previous work (e.g. N_H ~ 3 × 10²¹−2 × 10²² cm⁻²; Williams et al. 2023; Vaia et al. 2025) follow the predicted input spectrum suggested by the best-fit grain properties.