Difference between the merger fraction measured in the test sets with and without injected PSF (f_{merger with PSF} − f_{merger without PSF}) as a function of the contribution of the PSF. The filled (empty) symbols refer to the test sets with an intrinsic merger fraction of 5% (10%). Symbols are shifted slightly along the x-axis to prevent overlapping with each other. The main difference is observed in z-bin 3 at PSF contribution levels of 80% and 90%.