The temperature-weighted gravity vs. the geometric ﹩{M}_{K{\rm{s}}}﹩ (the left panel) and the spectroscopic ﹩{M}_{K{\rm{s}}}﹩ (the right panel). The temperature-weighted gravity is adopted as a “ground-truth” luminosity indicator. Only stars with precise Gaia parallax (﹩\widetilde{\omega }/{\sigma }_{\widetilde{\omega }}\gt 10﹩) are shown. The solid line is a second-order polynomial fit to the geometric ﹩{M}_{K{\rm{s}}}﹩ as a function of the temperature-weighted gravity. The circle with error bar in pink highlights the LB-1 B-star companion. The spectroscopic ﹩{M}_{K{\rm{s}}}﹩ estimate for LB-1 is perfectly consistent with the temperature-weighted gravity. The geometric ﹩{M}_{K{\rm{s}}}﹩ is brighter than the prediction from the gravity.