  A plethora of correlated and exotic metallic states have been identified on
the border of itinerant magnetism, where the long-range spin texture is melted
by tuning the magnetic transition temperature (T$_C$) towards zero, referred to
as the quantum phase transition (QPT). So far, the study of QPT in itinerant
magnets has mainly focused on low-T$_C$ materials (i.e., typically T$_C$ ~ 10
K) where the modification of electronic band structure is subtle, and only
makes a small contribution to the QPT. Here we report a distinct example of a
magnetic QPT accompanied by a gigantic modification of the electronic structure
in FeGe, i.e., a well-studied itinerant chiral magnet hosting
near-room-temperature (T$_C$ = 278 K) helical/skyrmion spin texture. The
pressure-driven modification of the band structure (e.g., reduction of exchange
splitting) is evidenced by magneto-transport study, suggesting a Fermi-surface
reconstruction around the magnetic QPT (P ~19 GPa), in stark contrast to the
case of typical metallic ferromagnets. Further application of pressure leads to
a metal-to-insulator transition above P > 30 GPa, as also corroborated by our
density-functional theory (DFT) calculation. Of particular interest is the
occurrence of anomalous magneto-transport in the inhomogeneous short-range
chiral-spin ground state (P = 20-30 GPa) above the QPT, with longitudinal
fluctuations of magnetization. The unexpected observation of spontaneous
anomalous Hall effect in this exotic quantum regime suggests macroscopic
time-reversal symmetry (TRS) breaking, even in the absence of long-range
magnetic order. Our findings mark the large body of unexplored high-T$_C$
itinerant magnets with broken inversion-symmetry as promising candidates of
novel ground state formation near QPT.
