Return plots for GEV fit of extreme values extracted from the duration (bottom), peak flux (middle) and fluence (top) of the GRO-BATSE catalogue (left), and Fermi-GBM catalogue (right). The 95% credible region is also shown. The model cannot interpret the return level of GRB 221009A for the fluence and peak flux while this event is part of the general distribution for duration. The insets show the results of the fit excluding GRB 221009A from the data set. GRB 230307A and GRB 130427A, respectively the second and third event with the highest fluence in the Fermi-GBM catalogue, are on the bright side, yet they are still consistent with GEV distribution (they are within the 99% credible region for a data set of 207 events).