Left panel: Comparison of the stacked profiles of eFEDS-detected groups (red-shaded region) and undetected groups (blue-shaded region) within a halo mass bin of 13.4 < log(M₂₀₀/M_⊙) < 13.7. Additionally, the orange-shaded region shows the stacked profiles from mock eRASS:4 observations for the eSASS-detected groups, while the light-blue-shaded region indicates the mock R11 undetected groups within the same halo mass bin. Right panel: Correlation between the residuals (ΔL_X) from the Lovisari et al. (2015)L_X, 500 − M₅₀₀ relation and gas mass concentration within the same halo mass bin as in the left panel. The Lovisari et al. (2015) relation has been chosen because it represents a very good fit for Magneticum (Marini et al. 2024; Popesso et al. 2025). Gas concentration is estimated as the ratio of gas mass within 0.1r₂₀₀ to the total mass within r₂₀₀. The red points represent predictions from the Magneticum simulation, while the blue line is the linear best fit. The squares correspond to ratios measured from the observed stacked profiles in the left panel, with the red square indicating the location of detected eFEDS groups and the blue square showing the result for undetected groups.