  Causality and the generalized laws of black hole thermodynamics imply a
bound, known as the \textit{Bekenstein--Hod universal bound}, on the
information emission rate of a perturbed system. Using a time-domain ringdown
analysis, we investigate whether remnant black holes produced by the
coalescences observed by Advanced LIGO and Advanced Virgo obey this bound. We
find that the bound is verified by the astrophysical black hole population with
$94\%$ probability, providing a first confirmation of the Bekenstein--Hod bound
from black hole systems.
