  Context. Weak gravitational lensing offers a powerful method to investigate
the projected matter density distribution within galaxy clusters, granting
crucial insights into the broader landscape of dark matter on cluster scales.
Aims. In this study, we make use of the large photometric galaxy cluster data
set derived from the publicly available Third Data Release of the Kilo-Degree
Survey, along with the associated shear signal. Our primary objective is to
model the peculiar sharp transition in the cluster profile slope, that is what
is commonly referred to as the splashback radius. The data set under scrutiny
includes 6962 galaxy clusters, selected by AMICO - an optimised detection
algorithm of galaxy clusters - on the KiDS-DR3 data, in the redshift range of
0.1 < z < 0.6, all observed at a signal-to-noise ratio greater than 3.5.
Methods. Employing a comprehensive Bayesian analysis, we model the stacked
excess surface mass density distribution of the clusters. We adopt a model from
recent results on numerical simulations that capture the dynamics of both
orbiting and infalling materials, separated by the region where the density
profile slope undergoes a pronounced deepening. Results. We find that the
adopted profile successfully characterizes the cluster masses, consistent with
previous works, and models the deepening of the slope of the density profiles
measured with weak-lensing data up to the outskirts. Moreover, we measure the
splashback radius of galaxy clusters and show that its value is close to the
radius within which the enclosed overdensity is 200 times the mean matter
density of the Universe, while theoretical models predict a larger value
consistent with a low accretion rate. This points to a potential bias of
optically selected clusters preferentially characterized by a high density at
small scales compared to a pure mass-selected cluster sample.
