Left: Lyα luminosity functions (LALFs) at z = 2,3, and 4 (from top to bottom, respectively) in the full volumes of TNG300 (solid) and TNG100 (dashed) in black together with the uncertainties computed via jack-knife sampling. Like the UVLF case, the TNG300-based measures are underestimated at the faint end due to the poorer mass resolution. Literature measurements include Sobral et al. (2018a, blue symbols), Konno et al. (2016, orange circles and squares), Ouchi et al. (2008, green squares and triangles), Dawson et al. (2007, orange triangles), Zheng et al. (2013, red triangles). In all three panels, blue solid curves show the best-fit Schechter function of Sobral et al. (2018a). Right: LALFs measured within (15 cMpc)³ cubic volumes centered on massive protoclusters are shown as gray lines and shades (PC15 boxes). The field LALFs are repeated in black. Two red dashed curves in each panel indicate the best-fit Schechter functions for the TNG100 measures. The lower red-dashed curve is for the field regions and the higher red-dashed curve is for the protoclusters.