Upper panel: completeness of the optical group catalogs based on the Magneticum mock galaxy catalog per bin of M_200, FoF best proxy for R11 (red lines), T17 (orange lines), and Y05 (magenta lines) as obtained in Marini et al. (2024). The black line indicates the completeness of the X-ray selected sample extracted from the eROSITA mock observation with the eSASS detection algorithm as a function of the input M₂₀₀ of Magneticum, as the X-ray selection algorithm gives no other mass proxy. Bottom panel: contamination of the optical group catalogs based on the Magneticum mock galaxy catalog per bin of original M₂₀₀ of Magneticum for R11 (red lines), T17 (orange lines), and Y05 (magenta lines) as obtained in Marini et al. (2024). The black line indicates the contamination observed in the eSASS X-ray selected sample.