Observed X-ray (0.2 − 2.3 keV) luminosity distribution as a function of redshift. The top panel is colour-coded according to the number density in the logarithmic scale, while the bottom panel is colour-coded by spectroscopic completeness. The dashed line indicates the flux limit of the eROSITA survey, while the filled line indicates the location of the knee of the soft X-ray luminosity function according to the LADE model of Aird et al. (2015). The dotted horizontal line indicates the limit of L_{0.2 − 2.3keV} ≤ 10⁴² erg s⁻¹ applied in Sect. 5 for a pure AGN selection.