Impact of contamination from spurious (“false”) fields on temperature, normalization, and fit statistics in the stacked sample from the MAGNETICUM mock observations equivalent to eRASS:4 depth. The top panel shows the measured temperature as a function of the fraction of false sources included in the sample. The middle panel presents the corresponding normalization values, which decrease with increasing contamination. The bottom panel shows the reduced statistic of the spectral fit, which increases with contamination. Error bars indicate 3σ uncertainties.