  We argue for the matching of 1-loop divergences between 4d Chern-Simons
theory with Disorder defects and the corresponding integrable 2d sigma-models
of non-ultralocal type. Starting from the 4d path integral, we show under
general assumptions that the 1-loop divergences localise to the 2d defects.
They match the 'universal' formulae developed in [arXiv:2209.05502] for the
1-loop RG flows of integrable 2d sigma-models. Our argument uses an alternate
path integral representation for the 1-loop effective action and the known
classical equivalence between the 4d and 2d theories.
