  With the growing number of binary black hole (BBH) mergers detected by
LIGO/Virgo/KAGRA, several systems have become difficult to explain via isolated
binary evolution, having components in the pair-instability mass gap, high
orbital eccentricities, and/or spin-orbit misalignment. Here, we focus on
GW191109\_010717, a BBH merger with component masses of $65^{+11}_{-11}$ and
$47^{+15}_{-13}$ $\rm M_{\odot}$, and effective spin $-0.29^{+0.42}_{-0.31}$,
which could imply a spin-orbit misalignment of more than $\pi/2$ radians for at
least one of its components. Besides its component masses being in the
pair-instability mass gap, we show that isolated binary evolution is unlikely
to reproduce the proposed spin-orbit misalignment of GW191109 with high
confidence. On the other hand, we demonstrate that BBHs dynamically assembled
in dense star clusters would naturally reproduce the spin-orbit misalignment
and the masses of GW191109, and the rates of GW191109-like events, if at least
one of the components were to be a second-generation BH. Finally, we generalize
our results to all the events with a measured negative effective spin, arguing
that GW200225 also has a likely dynamical origin.
