Why does Zenless Zone Zero stutter on a PCCOOLER RZ820?

ZZZ street battles were lagging; the RZ820 temp fluctuated wildly. I maxed the fan, but it was too noisy. AIDA64 showed a 10℃ swing causing frame delay. I used the GamePP Fan Curve Panel for dynamic speed: low below 65℃, rising above 75℃. AIDA64 confirmed the swing dropped to 3℃. Stable at 65-70℃. Smooth action now.