X-ray flare energies from exponential fits normalized to R₀ versus TESS flare energies. The energies calculated from fits made to the synthethic flare peaks (red) and normalized to R₀ are compared with those made to the synthetic flare peak scaled down by a factor two (left panel, green circles) and up by factor two (middle panel, teal circles) respectively, and from fits made to the original synthetic peak but integrated over the flare light curve starting from the first eRASS bin (right panel, light green diamonds). The peculiar flares described in Sect. 7.5.4 are marked as blue crosses. The black line denotes equal optical and X-ray flare energies.