In this work, our focus is on investigating the rate modification of ground-state chemical reactions inside an optical cavity. We emphasize the necessity to calculate the rate using the rigorous formula Eq. ( ) to avoid artifacts emanating from the transient dynamics which can lead to spurious resonance peaks in the cavity-modified rate. By exclusively treating the optical mode of the cavity classically, we have found that the resonant peak in the cavity frequency-dependent rate profile, observed in the fully quantum-mechanical simulations, is absent. This absence confirms our assumption that the resonant peak arises from a process involving the resonant energy exchange between the cavity mode and the molecular vibrations, which necessitates explicit consideration of both quantized cavity photonic states and discrete molecular vibrational states. Importantly, this finding strongly hints that the resonant rate alternation observed in vibrational strong coupling experiments inside optical cavities is essentially a macroscopic quantum phenomenon.