Retrieved volume mixing ratios for H₂O of the HST 2018 maximum brightness spectrum (left). Four retrieval runs were conducted: a vertically uniform and a non-uniform H₂O abundance profile one for each of the two fixed surface gravity values of log g = 4.268 ± 0.006 (low) and log g = 4.45 ± 0.03 (high). Right panel shows the corresponding posterior median spectra (F) for all four runs and differences between them (∆F). The HST 2018 maximum brightness spectrum data is shown as black dots with associated uncertainties.