X. -L. Wang, Z. Yan, F. -G. Xie, J. -F. Wang, Y. -X. Li, Z. -Y. Liu, R. -Y. Ma

Type-C quasi-periodic oscillations (QPOs) in black hole X-ray binaries are sensitive probes of accretion geometry. Using Insight-HXMT observations of MAXI J1348-630, we study the evolution of type-C QPOs during its 2019 main outburst and later mini outbursts. We carry out timing and spectral analysis, tracking QPO frequency, fractional rms, energy dependence and their correlations with flux and spectral shape. The QPO frequency increased from 0.24 Hz to 7.28 Hz during the rise and remained near 7 Hz when reappearing in different states. The rms spectrum hardened after the transition from hard to hard-intermediate state. The frequency-flux relation shows strong hysteresis between rise and decay, with the loop reversed between main and mini outbursts. In contrast, frequency and hardness follow a tight single-track anti-correlation. Our results support that the Compton region can reform at a characteristic scale. The QPO frequency is mainly driven by spectral shape rather than luminosity. The reversed hysteresis suggests differences between main and mini outbursts related to initial conditions.