The brains of all ten people would be making a "best guess" of what they are observing and it would be dependent on their POV.
Consider: a train track with a moving train at speed which is blowing it's whistle (wave frequencies). Behind the receding train stand 5 people and they all agree that the train whistle's frequency is the note of "c". At the other end of the track are 5 people listening to the train whistle as it approaches them and they all agree that the whistle's frequency is "d ".
Of these 10 observers, who is telling the truth and who is wrong?
They are all telling the truth and they are all wrong . The actual frequency of the train whistle is c# . The Doppler effect presents a "modified" frequency to all observers.
A photon does have a mathematical (quantum) value but this not a physical property. A photon is not "matter" it is a quanta of energetic value with a wavelength.
Abstract
https://www.sciencedirect.com/science/article/pii/S2211379719330943#
Photons
Last updated May 18, 2020
As Described by Maxwell's Equations
Creation of Photons Blackbody Radiation
Spontaneous Emission
https://chem.libretexts.org/Bookshe...mental_Concepts_of_Quantum_Mechanics/Photons#
How does any this prove your threads point ?