Projected number of galaxies in various simulations. We search for galaxies following the same configuration of ALMA band 7 (d = 30″). We include the results from the lightcones of semi-empirical models (Béthermin et al. 2017; Popping et al. 2020), semi-analytic models (Lagos et al. 2019, 2020), and hydrodynamical simulations (Lovell et al. 2021). The shadows show the 1σ, 2σ, 3σ, and 5σ scatter in the lightcones of the SHARK simulation (Lagos et al. 2019). Error bars indicate the Poisson errors. Within the simulations it is very rare (> 5σ) to find the number of SMGs seen around J0217−0820, but the deeper the observation goes, the stronger the projection effect.