QPEs volumetric rates. Top: Distribution of the four eROSITA QPEs (A21; A24) in the luminosity-redshift plane. Bottom: X-ray luminosity function of eROSITA QPEs (green), expressed both in Mpc⁻³ and per galaxy, as a function of the average peak 0.5 − 2.0 keV luminosity. The three bins adopted in are 41.7 − 42.3, 42.3 − 42.8 and 42.8 − 43.3, respectively containing two, one and one QPE. The green line and related contours represent the median and 16th–84th percentiles of the fit power-law model, with a slope ≈ − 2. The two gray points represent the rates from eRO-QPE1 and eRO-QPE2 alone (A21) in two bins of 1 dex, to highlight the small effect of adding new discoveries.