Yes it always has been the explaination of why it interference with itself in that the waves pass thru both slits. We don't talk about the part of the wave that are also going away from the slits but however lets do that now.
So our photon wave passes thru slits and is on is half way on it's way to a view point we have setup to see the normal interference. At that exact instant we actually observe the photon at the point the same distance behind the source point and away from the slits so our "part of the wave" we are observing hasn't gone thru any slits. The observation collapses the wave to that single point and it shows no interference pattern at all, it reflects the conditions of the part wave that we encountered only.
The key point to this is each part of the wave seems unconnected to other parts of the wave and they know nothing of each others histories. The collapse to a point only reflects the history of the wave reaching the observation point.
This is what make photons tricky because you can't make them real or energy or having interactions until they collapse to a point. Good old Prof Matt Strassler in his articles does a good job on it
https://profmattstrassler.com/articles-a...alse-dichotomy/He basically ends up saying the same thing we all do, quote "Photons should not be called `energy’, or `pure energy’, or anything similar."
The key point that determines what happens with a photon is at collapse point and you really can't construct histories or interactions with anything until you have a collapse point. It is what makes your OP statement misguided and what makes the double slit experiment do peoples head in especially in things like delayed choice and quantum eraser experiments when they construct histories and say things like well the photon has passed thru the slit ... well no it didn't until it collapses to a point.
So the answer to your OP question is the photon doesn't change energy and can't. The energy difference is simply a reflection of the energy differences between the background of the source point and the point of measurement.
The thing to ponder is does that mean even a point in empty space has energy or is the energy background something to do with being able to measure?
