Impact of AGN contamination on XXL selection function in the CR–r_c parameter space. We considered two cases: a pure case where no clusters are missed due to AGN contamination (left), and the measured missed fraction from XXL, constituting 5% of the cluster population. The detection probability is reduced in the case of 5% missed clusters, particularly in the CR > 0.1 region, reinforcing the hypothesis that very peaked clusters are excluded by the C1 selection alone.