Examples of observed spectra with best-fit models (left, including background, shown with a grey-dashed line) and modelled spectral energy distributions (right, without background) of three states, selected taking the 10th, 50th, and 90th percentile of log F_cor in a narrow range of F_disc (namely around a ±0.05 dex of the median log F_disc). Both data and models are colour-coded with the fit Γ, highlighting a softer-when-brighter trend in log F_cor. These three states are represented by red-contour data points in the bottom panel of Fig. 7.