Spectral evolution of QPEs. Darker to lighter colors represent the evolution from the start to end of the eruptions, color-coded as in the legend as a function of the epoch. The top right (medium right) panel shows the QPE bolometric luminosity (temperature) evolution with respect to the eruptions phase. The top left panel shows their coevolution. The bottom right panel shows the evolution of the emitting radius, assuming a thermal spectrum and spherical geometry.