It makes it different and gets us closer to understanding it. Right now, we have no idea what dark energy actually is, it’s just the name of the phenomenon of ever-accelerating expansion. Like, something is driving that expansion, and we call that something dark energy.

The simplest model — ΛCDM, assumes that there’s vacuum energy that’s constant throughout the universe, and that it’s what’s causing the expansion. Check my comments below for more info. There are other models too, like a modified gravity theory where it behaves as a repulsive force instead of an attractive one when applied on massive scales.

What this paper seems to be closer to is Quintessence. It assumes that dark energy is something like a field that can change over time and across space. I’ll make us revise general relativity (since cosmological constant is, well, constant in GR), but hopefully will get us closer to understanding the inner workings as a whole.

ELI5-ish: our current best guess is the universe is expanding because it kinda just fundamentally does that. It’s a property of space itself. If the paper turns out to be right in some way, then there’s some actual thing, not a property, that fills the universe, and that thing is what’s pushing everything apart. And there can be more or less of that thing making the universe expand differently at different times or within different regions. Or something else even, we’ll have to run a lot of experiments to figure it out.

Edit: so I read the original paper, and my initial assessment was wrong. It uses a hybrid model instead of plain quintessence or CCC-type model to demonstrate a better-fitting explanation, but the model itself is most likely not viable as an actual representation of reality.

Also, to clarify the difference between Quintessence and CCC. These are somewhat similar, but focus on different things. In quintessence, dark energy is believed to be a field-type thing, so it can naturally have different concentrations across time and space. In CCC, cosmological constant is assumed to be time-varying, but the theory doesn’t really describe what dark energy is, only how it behaves. Could be a field, but also could be something else. It doesn’t specify.