  The gravitational wave signals detected by the LIGO-Virgo-KAGRA collaboration
can be explained by mergers of binary primordial black holes (PBHs) formed in
the radiation dominated epoch. However, in early structures induced by the
Poisson distribution of PBHs, a significant fraction of binaries are perturbed
and avoid mergers. In addition, the internal dynamics of early halos lead to
the formation of dense primordial black hole clusters within a few Hubble times
from the moment of halo formation. In such clusters PBH binaries are
effectively formed and their mergers potentially dominate in the modern era. We
obtained that the PBH merger rate changes with redshift as $\mathcal{R} \propto
(1 + z)^\beta$, where $\beta = 1.4 - 2.2$ reflects the influence of PBH
clustering and depends on both $z$ and $f_{\rm PBH}$. The observed merger rate
constraints the fraction of PBHs of tens solar masses in the composition of
dark matter $f_{\rm PBH} \lesssim 0.001 - 0.1$ in dependence of the clustering
efficiency.
