SEDs of all known radio-loud quasars at z > 6 and P352–15 at z = 5.832. The filled symbols are measurements of the 250 GHz continuum flux density (NOEMA measurements presented in this paper and literature data from ALMA for J2318−3113 Venemans et al. 2020). The solid lines are MBB model (with T_dust = 47 and β = 1.6) scaled to the observed continuum flux density. The dotted lines are the power law (broken power law in the case of J0309+2717 and J1429+5447) fits to the radio data from the literature (Bañados et al. 2021; Condon et al. 1998; Frey et al. 2008, 2011; Ighina et al. 2021a; Intema et al. 2017; Momjian et al. 2008; Shimwell et al. 2019; Wang et al. 2011). The literature data are shown with thin diamonds and the NOEMA data for our sample with squares. Different colors correspond to each of the radio-loud quasars as indicated in the legend. The shaded area shows the region below the 3σ limit for continuum flux density of P172+18, which is not detected with NOEMA.