Time evolution of the ratio between the abundances predicted by the model that considers initial atomic abundances (main paper) and the abundances as given by the pre-phase model (this section). The solid line represents the mean ratio, while the shaded area delimits the interquartile range. For generating these plots, we only considered density values between percentiles 1.5% and 98.5% of the density PDF analysed in the main core of the paper, which roughly corresponds to n_H = 1.40 × 10⁴ cm⁻³ and n_H = 1.20 × 10⁵ cm⁻³.