Why does Battlefield V drop from 144 to 40 FPS in multiplayer?

Charging into enemy lines was great until my frame rate plummeted from 144 to 40, feeling like I hit a brick wall. I tried enabling PBO Auto-Overclocking in BIOS; while peak FPS rose, my 1% lows actually dropped further, which was infuriating. I used the GamePP Power Plan Switcher to lock the system into Ultimate Performance mode. HWiNFO showed voltage fluctuations narrowed to ±5mV from ±20mV, RTSS confirmed FPS stayed above 110, and AIDA64 verified CPU temps at 78-84℃.