Top: surface brightness profiles of redMaPPer clusters in three redshift bins. These profiles were presented by Y. Zhang et al. (2024), each consisting of over 1000 stacked clusters. Middle: derived slopes of the surface brightness profiles in different redshift bins. Note the dip feature between 20 and 100 kpc in all of the profiles at the CG outskirts. Bottom: the local minima of the dips are identified to be between 42 and 52 kpc and do not seem to have significant dependence on cluster redshift.