Experimental data have provided intriguing hints for the violation of lepton flavor universality (LFU), including $B\to D^{(*)}\tau \nu /B\to D^{(*)}\ell \nu$, the anomalous magnetic moment of the muon and $b\to s{\ell }^{+}{\ell }^{-}$ with a significance of $>3\sigma$, $>4\sigma$, and $>5\sigma$, respectively. Furthermore, in a recent reanalysis of 2018 Belle data, it was found that the forward-backward asymmetry ($\mathrm{\Delta }{A}_{\mathrm{FB}}$) of $B\to D^{*}\mu \overline{\nu }$ vs $B\to D^{*}e\overline{\nu }$ disagrees with the SM prediction by $\approx 4\sigma$, providing an additional sign of LFU violation. We show that a tensor operator is necessary to significantly improve the agreement with data in $\mathrm{\Delta }{A}_{\mathrm{FB}}$ while respecting the bounds from other $b\to c\ell \nu$ observables. Importantly, this tensor operator can only be induced (at tree-level within renormalizable models) by a scalar leptoquark. Furthermore, among the two possible representations, the $SU(2{)}_L$-singlet $S_1$ and the doublet $S_2$, which can interestingly both also account for the anomalous magnetic moment of the muon, only $S_1$ can provide a good fit. Even though the constraints from (differences of) other angular observables prefer a smaller value of $\mathrm{\Delta }{A}_{\mathrm{FB}}$ than the current central one, this scenario is significantly preferred (nearly $4\sigma$) over the Standard Model hypothesis, and is compatible with constraints such as $B\to K^{*}\nu \nu$ and electroweak precision bounds. Therefore, if the $\mathrm{\Delta }{A}_{\mathrm{FB}}$ anomaly is confirmed, it would provide circumstantial evidence for scalar leptoquarks and pave the way for a natural connection with all other anomalies pointing toward LFU violation.

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• Leptonic, semileptonic & radiative decays
• Particle interactions
• Leptoquarks