One way to explain it would be if cosmic redshift were due to some other optical effect, than recession of the source/expansion of space.

So rather than assuming the rate drops off rapidly, after the initial event, what we see, from our point of view outward, is an effect that compounds on itself, so the further away, the more the rate goes parabolic, until the point where it appears to recede at the speed of light.

Originally it was assumed redshift was due to conventional doppler effect and everything is moving away from a central point, but it became apparent that redshift increases proportional to distance in all directions, making us appear to be at the center of the universe.

So it was changed from an expansion in space, to an expansion of space, because "spacetime!" Even though this would mean the speed of intergalactic light is not constant to intergalactic space.

Consider the third illustration in this article, where light is modeled as a wavy line, that gets stretched as the bubble expands; For one thing, the wave action of light is a function of its motion, so it makes no sense to model the frequency of light as somehow traveling a different space than what the speed of that light is measuring. Yet that is what is proposed, that the speed and spectrum of the same light describe different metrics of space.

Meanwhile the speed is still being treated as the denominator in this theory, or it would be a "tired light" theory, if the speed were the numerator.

The problem is the only apparent way to explain redshift of light is increasing distance, even if it's fudged to say the space is expanding, though the light doesn't speed up, in order to remain constant.

It has been observed that while single spectrum light will only redshift due to recession, multi-spectrum light "packets" do redshift over distance, as the higher frequencies dissipate faster.

Which would mean we are sampling a wave front, not observing individual photons.

Though this would mean that quanta of light, aka, photons, are a function of absorption and measurement, not of the actual light traveling. Such that the further light travels, the more frequencies are bound up in particular quanta of light. Rather than individual photons traveling billions of lightyears.

Suffice to say, the evidence will have to become overwhelming, to the point such enormous patches, such as Inflation, Dark Matter and Dark Energy, go beyond ludicrous, before the field can consider alternatives.