L_iso–E_p relation using different timing intervals. Left: Correlation between L_iso and E_p for the four MGF candidates, GRB 231115A (light blue), GRB 051103 (pink), GRB 200415A (black), and GRB 180128A (gray), revealing an approximate $L_{\mathrm{iso}}\propto E_{\mathrm{p}}^2$ relationship that is a strong signature of relativistic winds. The temporal binning is uniformly fixed intervals and uses the values in Table B.1. Right:L_iso and E_p for all four transients over the BB intervals in Tables 1 and C.1, omitting the unconstrained E_p intervals of GRB 051103. These data were fit using the fitting method described in Appendix A, which is able to fit data with asymmetric uncertainties. All fit uncertainties and uncertainty bars are at the 90% confidence level.