False-alarm probability (FAP) of observing Bayes Factors from GW231123-like unlensed signals. The curves are generated by analyzing 100 unlensed NRsur signals injected into Gaussian noise with lensed and unlensed hypotheses. The shaded region shows the Poisson error. Horizontal lines show the corresponding confidence levels (c.l.s). The GW231123 Bayes factor lies outside the distribution, with an FAP <1% and significance ≳2.6σ.