It’s probably not that the light is losing energy it’s just that the distance it travels over time (the time we “know” is supposed to take for a given distance) appears compressed because of unknown/unseen gravitational forces.

This doesn’t seem to be at all what tired light proposes though. What you’re explaining sounds like red-shift due to an expanding universe. From what I can tell they claim it actually loses energy through interaction with “other things” in the universe.