When directly simulating C via the average potential response of MD runs biased with excess charges σ = -29.19 . . . 29.19 µC/cm 2 (see SI for further details), we indeed observe a much higher capacitance peak in the vicinity of the potential of zero charge (PZC) for the two DFT-based methods (cf. Fig. ). Peak shape and magnitude (C DFT max > 100 µF/cm 2 ) are similar as in other DFT-AIMD works and not inconsistent with experiments . In contrast, FF-derived capacitances are extremely low (C FF max < 10 µF/cm 2 , solid purple line in Fig. ) and decrease even further (C FF max ∼ 3 µF/cm 2 ) if we reevaluate the FF using the arguably more realistic DFT-PCH water trajectory (dashed purple line in Fig. ). This dramatic underestimation of C in the FF simulations agrees with reported FF results with explicit electrolyte ions , confirming the previous hypothesis that interfacial electrostatic potential drops are strongly overestimated due to the unrealistic electronic excess charge distributions in FF methods. Certainly, the DFT charging methods lead to some (unavoidable) methodological artifacts, namely spurious excess charges either within the bulk of the metal (DFT-HBG) or within bulk water (DFT-PCH) (Fig. ), which is why the reported DFT capacitance values need to be taken with a grain of salt, too. Nonetheless, overall this does not affect the central advance achieved at this level of theory, in that there is a significant spillover of electronic charge into the interfacial water region.