  We revisit the $L_\mu - L_\tau$ extension of the Standard Model that can
simultaneously address anomalies in semileptonic $B$ meson decays and the
nature of dark matter (DM). In the region favored by the $B$ anomalies, this
scenario is excluded by a combination of low-energy flavor constraints and
stringent DM direct detection constraints if the kinetic mixing between
$Z^\prime$ gauge boson and the photon vanishes at high energy scales, since
this leads to a sizable coupling between DM and the SM in low-momentum
scattering processes. However, this is no longer the case if the kinetic mixing
vanishes at low energy scales instead. In this scenario, the low-momentum DM
scattering rate can be suppressed and constraints from direct detection
experiments can be substantially relaxed. As a result, we find a re-opening of
the region of parameter space where the $B$ anomalies and DM can be
simultaneously explained.
