Light, i.e. photons, travel at the maximum speed we know of in the universe.
Einstein’s e=mc^2^ shows us that when “the speed of light” is achieved travel forward or backward on the time line is possible.
Therefore a photon exists only for an instantaneous amount of time, regardless of how far it travels, from the perspective of the photon.
The light that the JWST captures from 12.3 billion years ago is that old to us. To the photon, however, it was created in that stellar object and then immediately crashed into the JWST sensor.
The membrane of time is what we perceive not what the photon experiences.