  Anomalous metallic behavior, marked by a saturating finite resistivity much
lower than the Drude estimate, has been observed in a wide range of
two-dimensional superconductors. Utilizing the electrostatically gated
LaAlO3/SrTiO3 interface as a versatile platform for superconductor-metal
quantum phase transitions, we probe variations in the gate, magnetic field, and
temperature to construct a phase diagram crossing from superconductor,
anomalous metal, vortex liquid, to Drude metal states, combining longitudinal
and Hall resistivity measurements. We find that the anomalous metal phases
induced by gating and magnetic field, although differing in symmetry, are
connected in the phase diagram and exhibit similar magnetic field response
approaching zero temperature. Namely, within a finite regime of the anomalous
metal state, the longitudinal resistivity linearly depends on field while the
Hall resistivity diminishes, indicating an emergent particle-hole symmetry. The
universal behavior highlights the uniqueness of the quantum bosonic metallic
state, distinct from bosonic insulators and vortex liquids.
