Halo mass of SPT0311–58 together with a compilation of z > 2 protoclusters as a function of redshift (see text). The orange lines correspond to the halo accretion history of the 25 most massive clusters at z = 0 in the IllustrisTNG simulation discussed by Lim et al. (2021). The FLAMINGO simulations are taken from Lim et al. (2024), and represent the median and the full range among the 100 highest-SFR haloes identified in each snapshot of its 2.8 Gpc and 1 Gpc box runs. The figure shows the extreme mass of SPT0311–58, being the most massive protocluster discovered so far at EoR. It also shows the difficulty of TNG simulations to predict a rare system like SPT0311–58, as a consequence of their limited simulated volume (i.e. box size of 300 Mpc). The position of SPT0311–58 can be reproduced by FLAMINGO simulations with larger box sizes (see text).