Number density of CMGs as a function of redshift, in units of co-moving Mpc⁻³. The black line and markers represent the TNG50 CMGs from this work. Colored lines and markers correspond to observational estimates from VIPERS (Lisiecki et al. 2023) in red, Scognamiglio et al. (2020) in orange, Damjanov et al. (2014) in green, van der Wel et al. (2014) in purple, Barro et al. (2013) in blue, and Ferré-Mateu et al. (2017) in dark green for the local relics, and magenta for Grèbol-Tomàs et al. (2023) compacts. Simulated CMGs show an increasing number density with redshift, consistent with models predicting more compact objects in the early Universe. A similar trend is seen in the observational data.