True.

The problem is that as overall redshift increases proportional to distance, it makes us appear to be at the center, so it was changed early on from an expansion in space, to an expansion of space, because "spacetime."

Which totally ignores the fact that if intergalactic light is being redshifted, it isn't constant to intergalactic space. More lightyears, not expanded lightyears.

Two metrics are being derived from the same light, one based on the speed and one based on the spectrum. Speed is still being assumed as the denominator, or it would be a "tired light" theory.

Basically light is being treated as a wavy line, that when stretched, becomes less wavy. Also ignoring how waves propagate.

I came across a paper year years ago, pointing out that while single spectrum light will only redshift due to recession, multispectrum light "packets" will redshift over distance, as the higher frequencies dissipate faster;

Currently it's on amazon servers, so the old link doesn't work, but google 2008CChristov_WaveMotion_45_154_EvolutionWavePackets.pdf

The further problem this creates, is it means we are not observing individual photons, but sampling a wave front, which suggests the quantification of light is a function of absorption and measurement, not fundamental to the actual light.

Also, if this effect compounds on itself, that would explain the curve in the rate, currently ascribed to dark energy.