Here is a much simpler explanation;

2008CChristov_WaveMotion_45_154_EvolutionWavePackets.pdf

In a nutshell, while single spectrum light will only redshift due to recession, multi spectrum wave packets will redshift over distance, because the higher frequencies dissipate faster. This makes cosmic redshift an optical effect, not evidence of expansion from an initial event. It would also mean we are sampling a wave front, not sensing individual photons that have traveled billions of lightyears, so the quantization of light would be an effect of absorption and measurement, not fundamental to the actual light.

So simple as it is, us mortals can understand why the field would go to multiverses and post empirical science, before looking that deeply into the models.

Obviously no one will take this seriously, but if the James Webb actually makes it up and works, is anyone willing to bet against the possibility we find the Cosmic background radiation to be the light of ever further sources, shifted off the visible spectrum, as those fine level variations come more in focus?