  ASASSN-14ko was identified as an abnormal periodic nuclear transient with a
potential decreasing period. Its outbursts in the optical and UV bands have
displayed a consistent and smooth "fast-rise and slow-decay" pattern since its
discovery, which has recently experienced an unexpected alteration in the last
two epochs, as revealed by our proposed high-cadence Swift observations. The
new light curve profiles show a bump during the rising stages and a
rebrightening during the declining stages, making them much broader and
symmetrical than the previous ones. In the last two epochs, there is no
significant difference in the X-ray spectral slope compared to the previous
one, and its overall luminosity is lower than those of the previous epochs. The
energy released in the early bump and rebrightening phases ($\sim10^{50}$ erg)
could be due to collision of the stripped stream from partial tidal disruption
events (pTDEs) with an expanded accretion disk. We also discussed other
potential explanations, such as disk instability and star-disk collisions.
Further high-cadence multi-wavelength observations of subsequent cycles are
encouraged to comprehend the unique periodic source with its new intriguing
features.
