The nature of the metallic ground state, in the transition from a superconductor to an insulator at a temperature close to absolute zero, is still a mystery. In this work, we uncover quantum oscillations of this quantum metal or failed superconductor in a three-dimensional anisotropic superconductor—lithium intercalated TiSe₂. The quantum metallic state, hosting saturating resistance below the superconducting transition even after properly filtering of radio-frequency (RF) signals, depends sensitively on the lithium doping. Exactly in this metallic regime, we show that the resistance oscillates as a function of magnetic field with a period that changes gradually with temperature. We attribute this oscillation to flux effects imposed by the domains of a coexisting charge density wave (CDW). It suggests that a periodically perturbed superconductor, either by CDW or artificial patterning, may be key to realizing the quantum metal.