  Since the discovery of dark matter-deficient galaxies, numerous studies have
shown that these exotic galaxies naturally occur in the $\Lambda$CDM model due
to stronger tidal interactions. They are typically satellites, with stellar
masses in the $10^8-10^9\;\mathrm{M}_\odot$ range, of more massive galaxies.
The recent discovery of a massive galaxy lacking dark matter and also lacking a
more massive neighbor is puzzling. Two possible scenarios have been suggested
in the literature: either the galaxy lost its dark matter early or it had been
lacking ab initio. As a proof of concept for the former assumption, we present
an example from IllustrisTNG300. At present, the galaxy has a stellar mass of
$M_\star \simeq 6.8 \cdot 10^9\; \mathrm{M}_\odot$, with no gas,
$M_\mathrm{DM}/M_\mathrm{B} \simeq 1.31$, and a stellar half-mass radius of
$R_{0.5,\star} = 2.45\;\mathrm{kpc}$. It lost the majority of its dark matter
early, between $z = 2.32$ and $z = 1.53$. Since then, it has continued to dwell
in the cluster environment, interacting with the cluster members without
merging, while accelerating on its orbit. Eventually, it left the cluster and
it has spent the last $\sim 2\;\mathrm{Gyr}$ in isolation, residing just
outside the most massive cluster in the simulation. Thus, the galaxy represents
the first example found in simulations of both an isolated dark matter-poor
galaxy that lost its extended envelope early and a fairly compact stellar
system that has managed to escape.
