QSO-DLAs binned data from Møller et al. (2013) with the high-redshift measurement of GRB 130606A (Hartoog et al. 2015) and GRB 210905A included. [M/H]_{100 km s⁻¹} is the metallicity expected for DLAs with ΔV₉₀ = 100 km s⁻¹ (zero-point normalization). The data of Møller et al. (2013) (filled circles) show a break in the evolution of the mass–metallicity relation at z ∼ 2.6 (dashed line), which is not confirmed by our measurement of GRB 210905A (filled triangle). We assumed for this point ΔV₉₀ = 359 km s⁻¹ and [M/H] = −1.71 ± 0.11, as explained in the text.