Li abundance (3D,NLTE) as a function of [Fe/H] for the N23 and GALAH DR3 sample stars (squares and circles respectively) with age colour-coded. Solid lines show the theoretical Li upper and lower envelopes (upper and bottom panels respectively) at different ages (see the legend), i.e., the maximum and minimum Li values at a given [Fe/H] and age expected from the models with $5800\mathrm{K}\lesssim T_{\mathrm{eff}}^{\mathrm{ZAMS}}\lesssim 6500$ K. We do not show it here, but the highest/ lowest A(Li) values for the models at [Fe/H] = −5.8 dex are 2.34/2.29 and 2.23/2.18 at the ages of 10 and 13 Gyr respectively. The dashed line shows the initial Li abundance assumed in the models. In the upper panel, the four-pointed stars show predictions from the models with log T₀ = 6.42 and solar metallicity from D21b with age similarly colour-coded.