Distribution of BL Lac classification probabilities (P_BLL) for all sources in the test set, as predicted by TabPFN. The X-axis represents P_BLL, indicating the predicted probability of a source being a BL Lac, while the colour of each bar corresponds to its true classification in the catalogue. The dashed vertical lines indicate the thresholds derived from the KDE analysis, marking regions where sources are most confidently identified as either BL Lac-like (P_BLL > 0.9) or FSRQ-like (P_BLL < 0.2).