  We present results from a 3.1 kg-day target exposure of two charge-coupled
devices (CCDs), each with 24 megapixels and skipper readout, deployed in the
DAMIC (DArk Matter In CCDs) setup at SNOLAB. With a reduction in pixel readout
noise of a factor of 10 relative to the previous detector, we investigate the
excess population of low-energy bulk events previously observed above expected
backgrounds. We address the dominant systematic uncertainty of the previous
analysis through a depth fiducialization designed to reject surface backgrounds
on the CCDs. The measured bulk ionization spectrum confirms with higher
significance the presence of an excess population of low-energy events in the
CCD target with characteristic rate of ${\sim}7$ events per kg-day and
electron-equivalent energies of ${\sim}80~$eV, whose origin remains unknown.

Cosmology and Nongalactic Astrophysics;High Energy Physics - Experiment;Nuclear Experiment