Same information as in Fig. 1, but here the x-axis shows the difference in z_spec with respect to the cluster redshift. This way we can identify spectroscopic cluster members (orange and green) as well as photometric cluster galaxies (red and green). Our fiducial measurement approach subtracts fore- and background interloper galaxies based on these relative numbers, after splitting the sample by galaxy type, and selecting similar sources in terms of stellar mass and projected radial distance from the cluster centres (cf. Fig. A.2).