Here is an interesting paper I came across some years ago;

https://fqxi.org/data/forum-attachments/2008CChristov_WaveMotion_45_154_EvolutionWavePackets.pdf

It makes the point that while single spectrum light will only redshift due to recession, multispectrum light "packets" will redshift over distance, as the higher frequencies dissipate faster.

Which opens a much larger can of worms, as it would mean we are sampling a wave front and the quantization of light is more an issue of measurement, than foundational to the light itself.

Which gets to another paper, arguing that very point;

https://fqxi.org/data/essay-contest-files/Reiter_challenge2.pdf

To add an interview that gives some historical context;

http://worrydream.com/refs/Mead%20-%20American%20Spectator%20Interview.html