We investigate the equilibrium quantum phase transition and critical phenomena in a Tavis–Cummings model that incorporates both an anti-squeezing term and the $A^2$ term (the square of the vector potential). The anti-squeezing term substantially reduces the critical coupling required for the phase transition, enabling the transition to occur without the need for ultrastrong atom-field coupling. Interestingly, when the $A^2$ term is included, the transition displays a reversed directionality: as the atom-field coupling increases, the system transitions from the superradiant phase back to the normal phase. We find that both ground-state entanglement and quantum superposition display correspondingly reversed behavior in the presence of the $A^2$ term. Moreover, we show that this reversed phase transition is accompanied by a dynamic crossover from chaotic to integrable behavior.