  CUPID-Mo is a cryogenic detector array designed to search for neutrinoless
double-beta decay ($0\nu\beta\beta$) of $^{100}$Mo. It uses 20 scintillating
$^{100}$Mo-enriched Li$_2$MoO$_4$ bolometers instrumented with Ge light
detectors to perform active suppression of $\alpha$ backgrounds, drastically
reducing the expected background in the $0\nu\beta\beta$ signal region. As a
result, pileup events and small detector instabilities that mimic normal
signals become non-negligible potential backgrounds. These types of events can
in principle be eliminated based on their signal shapes, which are different
from those of regular bolometric pulses. We show that a purely data-driven
principal component analysis based approach is able to filter out these
anomalous events, without the aid of detector response simulations.
