Survival functions of the fluence distribution from the S21 FAST bursts (Xu et al. 2022) with fluences larger than 0.5 Jy ms, together with an example survival function from a random ten-pulse subsample. The vertical lines indicate the optimal minimum fluence values from the PL fit. The example survival function does not show apparent flattening. Inset: Distribution of α_m for all 10⁴ ten-pulse subsamples (green) and those that do not show flattening (orange).