What quantum mechanical effect supports the White Dwarf remnant?

Electron degeneracy pressure, a quantum mechanical effect

After a low-mass star exhausts its core helium and sheds its outer layers to form a Planetary Nebula, the remaining core shrinks into an extremely dense object called a White Dwarf, roughly the size of Earth. This remnant is no longer supported by the thermal pressure generated by fusion, as the core never reaches the required temperature to fuse carbon. Instead, it is supported against the relentless inward pull of gravity by electron degeneracy pressure. This is a quantum mechanical effect where electrons resist being compressed into the same quantum state, effectively creating a strong internal resistance that prevents further gravitational collapse up to a certain mass threshold.