Summed eROSITA spectrum from 23 Ms of observations (“spec-z” sample). To reveal the intrinsic spectral shape of AGN, the spectrum is divided by the ARF and multiplied by E² (so the unit proportional to keV² Counts cm⁻² s⁻¹ keV⁻¹ or erg cm⁻² s⁻¹), normalized at 4 keV. The gray points are the unbinned data, while yellow circles show a logarithmic rebinning. The yellow shaded area, derived from bootstrapping the sample for 100 times, indicates the 68% uncertainty range of the spectrum from both stacking process and Poisson fluctuation (the plotting routine also applies to Figs. 4–8). Only the spectrum between 0.3 keV and 8 keV is used in this work. Between 1 and 6 keV, the spectrum is approximately linear in this log-log plot, while below, the spectrum bends upwards. Between 6 and 7 keV, a bump is visible despite the relatively larger errorbars. Power laws of typical photon indices are plotted only for visual comparison.