Same as Fig. 4, but now the model predictions are compared to the observed trends inferred for: (i) thin- and thick-disc dwarf stars from GES iDR5 (red and blue dots, respectively; Franchini et al. 2020, the vertical bars represent the standard deviations); (ii) high-Ia and low-Ia GALAH DR2 stars (red and blue upside-down triangles, respectively; Griffith et al. 2019). Zero-point shifts were applied to the data (see Sect. 2.1).