Mean stellar population properties of quiescent galaxies on the size–mass plane, and M_★/R_e vs. M_★. The panels from top to bottom display stellar metallicity (Z_★), and formation redshift (z_form). The solid red line is the best-fit size–mass relation for the quiescent population. The dashed black lines indicate the 1σ deviation from the best-fit relation. The stellar properties and quenching time were averaged using the LOESS method. Each hexbin contains at least five galaxies. In the top left corner of each panel we show the Spearman rank coefficient (ρ). (Panel a) Stellar properties from Gallazzi et al. (2025a) derived with BaStA (Gallazzi et al. 2005; Zibetti et al. 2017) (Panel b) Stellar properties from Kaushal et al. (2024) derived with Bagpipes (Carnall et al. 2018)