  The Lifshitz-Kosevich (LK) theory is the pillar of magnetic quantum
oscillations, which have been extensively applied to characterize a wide range
of metallic states. In this study, we focus on the Shubnikov-de Haas (SdH)
effect observed in SmSb, a rare-earth monopnictide. We observed a significant
departure from the expected LK theory near $T_N=2.4$~K: both a peak-like
anomaly and an enhancement in the temperature dependence of quantum oscillation
amplitude are seen in SmSb. Moreover, we discovered a remarkable sensitivity of
the SdH amplitudes to sample purity. By adjusting the sample purity, we were
able to tune the temperature dependence of the $\alpha$ band's SdH amplitudes
from a peak-like anomalous behavior to an enhancement. Therefore, SdH
oscillations from the $\alpha$ band connect the two well-known non-LK
behaviours, controllable through varying the sample purity, paving the way for
developing further understanding of the mechanism leading to the anomalous
quantum oscillations.
