A review of the spatially flat cosmological model SU(2) CMB , minimally induced by the postulate that the cosmic microwave background (CMB) is subject to an SU(2) rather than a U(1) gauge principle, is given. Cosmological parameter values, which are determined from the Planck CMB power spectra at small angular scales, are compared to their values in spatially flat 𝚲CDM from both local and global extractions. As a global model SU(2) CMB leans toward local 𝚲CDM cosmology and is in tension with some global 𝚲CDM parameter values. Spectral antiscreening / screening effects in SU(2) CMB radiance are presented within the Rayleigh-Jeans regime in dependence on temperature and frequency. Such radiance anomalies can cause CMB large-angle anomalies. Therefore, it is pointed out how SU(2) CMB modifies the Boltzmann equation for the perturbations of the photon phase space distribution at low redshift and why this requires to the solve the 𝓁-hierarchy on a comoving momentum grid (q-grid) for all z.

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