The simulated quasi-biennial oscillation (QBO) in Energy Exascale Earth System Model version 2 (E3SMv2) is characterized by a shorter period and stronger amplitude compared with its predecessor E3SMv1. This is primarily attributed to updates to the deep convective parameterization which makes convection more intense but less frequent while maintaining the time-mean convective heating tendency almost unchanged. Amplitudes of momentum fluxes associated with parameterized gravity waves, determined by the convective heating tendency square, are consequently intensified. In addition, stronger planetary waves, which is the other contributor to the QBO driving, are simulated in E3SMv2 in part due to tropospheric processes. Furthermore, there is evidence that planetary wave generation is present in the stratosphere due to dissipation of amplified parameterized gravity waves. These factors are found to be responsible for the stronger and faster QBO simulated in E3SMv2.