  The intracluster light (ICL) fraction is a well-known indicator of the
dynamical activity in intermediate-redshift clusters. Merging clusters in the
redshift interval $0.18<z<0.56$ have a distinctive peak in the ICL fractions
measured between $\sim 3800-4800$ \AA. In this work, we analyze two
higher-redshift, clearly merging clusters, ACT-CLJ0102-49151 and CL
J0152.7-1357, at $z>0.8$, using the HST optical and infrared images obtained by
the RELICS survey. We report the presence of a similar peak in the ICL
fractions, although wider and redshifted to the wavelength interval $\sim
5200-7300$ \AA. The fact that this excess in the ICL fractions is found at
longer wavelengths can be explained by an assorted mixture of stellar
populations in the ICL, direct inheritance of an ICL that was mainly formed by
major galaxy mergers with the BCG at $z>1$ and whose production is
instantaneously burst by the merging event. The ubiquity of the ICL fraction
merging signature across cosmic time enhances the ICL as a highly reliable and
powerful probe to determine the dynamical stage of galaxy clusters, which is
crucial for cluster-based cosmological inferences that require relaxation of
the sample.
