  Ultralight vector particles can form evolving condensates around a Kerr black
hole (BH) due to superradiant instability. We study the effect of near-horizon
reflection on the evolution of this system; by matching three pieces of
asymptotic expansions of the Proca equation in Kerr metric and considering the
leading order in the electric mode, we present explicit analytical expressions
for the corrected energy level shifts and the superradiant instability rates.
Particularly, in high-spin BH cases, we identify an anomalous situation where
the superadiance rate is temporarily increased by the reflection parameter
$\mathcal{R}$, which also occurs in the scalar scenario, but is largely
magnified in vector condensates due to a faster growth rate in dominant mode;
we constructed several featured quantities to illustrate this anomaly, and
formalized the magnification with relevant correction factors, which may be of
significance in future studies of gravitational waveforms of this monochromatic
type. In addition, the duration of superradiance for the whole evolution is
prolonged with a delay factor, which is calculated to be
$(1+\mathcal{R})/({1-\mathcal{R}})$ approximately.
