Hubble constant posteriors inferred from 137 BBH events using spectral sirens with four models (Flexible-BBH, PS paired, MLTP paired, and MLTP), together with the constraint from the bright siren GW170817 (B. P. Abbott et al. 2017). Vertical lines indicate the reference values from Planck and SH0ES Planck Collaboration et al. (2020) and A. G. Riess et al. (2022), highlighting the Hubble tension.