Magnitude distribution of metal-poor stars in our VMP catalogue into groups of MP, VMP, and EMP stars and magnitude distribution of stars with reliable metallicities from published GSP-Spec information (top). Metallicity distribution of our VMP catalogue and subsample with GSP-Spec published stars, good quality GSP-Spec stars, and reanalysed M22 VMP stars (bottom). Note: the metallicity distributions consists of metallicities inferred by each of the catalogues mentioned in the legend.