Posterior distributions of the Hubble constant inferred from spectral sirens using the Flexible-CBC, Flexible-BBH, MLTP-paired, and MLTP models, along with the constraint from the bright siren GW170817 (B. P. Abbott et al. 2017). Vertical lines mark the reference values from Planck and SH0ES Planck Collaboration et al. (2020) and A. G. Riess et al. (2022), highlighting the Hubble tension.