Comparison of the SED of the blackbody quasar BBQSORS (this study; black solid line) with those of the XRD (moss-green solid line; R. E. Hviding et al. 2026), transitioning LRDs (Forge I and II; blue and cyan lines, respectively; S. Fu et al. 2025), and stacked LRDs at z ∼ 6 (brown filled circles; H. B. Akins et al. 2025). Their optical-to-IR continua are broadly reproduced by (modified) blackbody models with different temperatures and dust extinctions, shown by the dashed and dotted lines. For reference, the median spectrum of normal quasars is also overplotted (thick gray solid line; G. T. Richards et al. 2006).