  Heavy-ion collisions, such as Pb-Pb or p-Pb, produce extreme conditions in
temperature and density that make the hadronic matter transition to a new
state, called quark-gluon plasma (QGP). Simulations of heavy-ion collisions
provide a way to improve our understanding of the QGP's properties. These
simulations are composed of a hybrid description that results in final
observables in agreement with accelerators like LHC and RHIC. However, recent
works pointed out that these hydrodynamic simulations can display acausal
behavior during the evolution in certain regions, indicating a deviation from a
faithful representation of the underlying QCD dynamics. To pursue a better
understanding of this problem and its consequences, this work simulated two
different collision systems, Pb-Pb and p-Pb at $\sqrt{s_{NN}} = 5.02$ TeV. In
this context, our results show that causality violation, even though always
present, typically occurs on a small part of the system, quantified by the
total energy fraction residing in the acausal region. In addition, the acausal
behavior can be reduced with changes in the pre-hydrodynamic factors and the
definition of the bulk-viscous relaxation time. Since these aspects are fairly
arbitrary in current simulation models, without solid guidance from the
underlying theory, it is reasonable to use the disturbing presence of acausal
behavior in current simulations to guide improvements towards more realistic
modeling. While this work does not solve the acausality problem, it sheds more
light on this issue and also proposes a way to solve this problem in
simulations of heavy-ion collisions.
