  The situation of the experimental data used in the dispersive evaluation of
the hadronic vacuum polarization contribution to the anomalous magnetic moment
of the muon is assessed in view of two recent measurements: $e^+e^- \to
\pi^+\pi^-$ cross sections in the $\rho$ resonance region by CMD-3 and a study
of higher-order radiative effects in the initial-state-radiation processes
$e^+e^- \to \mu^+\mu^-\gamma$ and $e^+e^- \to \pi^+\pi^-\gamma$ by BABAR. The
impact of the latter study on the KLOE and BESIII cross-section measurements is
evaluated and found to be indicative of larger systematic effects than
uncertainties assigned. The new situation also warrants a reappraisal of the
independent information provided by hadronic $\tau$ decays, including
state-of-the-art isospin-breaking corrections. The findings cast a new light on
the longstanding deviation between the muon $g-2$ measurement and the Standard
Model prediction using the data-driven dispersive approach, and the comparison
with lattice QCD calculations.
