S/N slices from Fig. 8 showing the S/N (vertical axis) as a function of the injected-model metallicity (horizontal axis). In the top panel, we show this result for CH₄, and CO is shown in the bottom panel. Different colours correspond to the different fixed p_c. Dashed lines correspond to S/N slices at the same fixed p_c from Fig. 6 of Grasser et al. (2024). Due to the unavailability of the original data, these values were extracted using WebPlotDigitizer (Version 5.2).