Under off-resonant conditions, the energy exchange between the cavity mode and molecular vibration is either energetically not allowed or kinetically ineffective. For instance, when ω c = 600cm -1 , a molecular transition necessitates the simultaneous emission or absorption of two photons, as depicted in Fig. (b), which has a low probability of occurrence when η c = 0.00125 a.u. . Consequently, the reaction rate undergoes a minimal change, as shown in Fig. . However, when the light-matter coupling strength is strong enough, for instance, η c = 0.01 a.u. , this multi-photon process becomes probable and gives rise to a side peak at round ω c = 600cm -1 , as demonstrated in Fig. . In the high ω c region, such as ω c = 1950cm -1 , the photon energy is close to the transition energy between v mol 1 ↔ v mol 4 as shown in Fig. ). Nevertheless, this vibrational transition is impeded by its low transition probability, governed by ⟨v mol 4 |x|v mol 1 ⟩. Additionally, the population in the photonic excited state diminishes with increasing ω c , which is shown in the SI.