Recall as a function of the number of transits calculated for a set of 10 000 synthetic transmission spectra of a TRAPPIST-1e twin, covering a wide range of stellar contamination scenarios. These spectra were generated starting from high-resolution spectra of Earth’s modern atmosphere (upper panel) and Earth’s Proterozoic atmosphere (lower panel). Dotted lines with squares and dashed lines with triangles represent the performance of MC and SC classifiers for CH|$_4$|⁠, O|$_3$|⁠, H|$_2$|O, and chemical disequilibrium (simultaneous CH|$_4$| + O|$_3$|⁠). The bc algorithm is shown as a continuous (purple) line.