Mass–radius diagram for young (≤1 Gyr) planets with precise age estimates (relative errors <50%). Planets are colour-coded based on their age, with a discrete colour bar at the top of the figure. Young planets with similar characteristics to TOI-5734b are labelled with their name. The Zeng et al. (2019) tracks, shown as dashed lines, are reported in the case of planets with an equilibrium temperature of T_eq = 700 K, 1 mbar pressure and the following compositions: 100% Earth-like, 100% H₂O, 100% rock (MgSiO₃), 50% Earth+50% H₂O, 99.9% Earth+0.1% H₂ envelope. The wide, horizontal grey line represents the ‘radius valley’.