  Gravitational vacuum condensate stars, also known as gravastars, have been
proposed as an alternative to black holes. Their interior contains a perfect
fluid with an equation of state akin to that of a cosmological constant. For
this reason, they have recently been considered as a possible astrophysical
source of dark energy. In this work we argue that gravitational vacuum
condensate stars cannot be the source of dark energy and highlight that a
direct coupling of their mass to the dynamics of the Universe would lead to an
additional velocity dependent acceleration, damping their motion with respect
to the cosmological frame. We briefly discuss the potential impact of this
additional acceleration in the context of a recent proposal that the observed
mass growth of compact objects at the core of elliptical galaxies might result
from such a cosmological coupling.
