Left panel: 2RXS vs. eFEDS count rates for the sources in common to both catalogues. The solid black line corresponds to the median count rate ratio of 5.8. The dashed lines correspond to a variability factor of 10 with respect to the median ratio (black solid line). Sources with variability factors >6 are marked with green or orange squares. Right panel: distribution of the variability factor. The orange line displays the standard normal distribution (unity scatter, zero mean).