Excess flux error versus Gaia EDR3 (ruwe) diagram showing the Final Parallax Selection (grey dots), the known hot subdwarfs in wide binary systems (blue circles), the known hot subdwarfs in close binary systems with WD, dM type, or BD companions (magenta squares), and the known hot subdwarfs where no binarity has been observed (yellow triangles). The red lines shows the variability cutoffs used for (ruwe) and flux error excess.