Dark energy is basically what we call a force that drives the ever-accelerating expansion of the universe. Something is pushing spacetime itself to expand in all directions simultaneously, and that something isn’t accounted for by any other fields or forces.
There is a cosmological constant associated with dark energy, Λ (lambda). It represents energy density of dark energy across our universe. This is why the article (and the paper itself) mentions ΛCDM model — that’s the simplest dark energy model, where vacuum has constant energy throughout the universe and that’s what drives the expansion. There’s a special parameter w, which is a ratio of pressure to energy density of dark matter. It currently seems to be exactly -1, but different values of w yield different predictions for future fate of the universe.
What you need to know about w, is that if it’s exactly -1, it means that dark energy is indeed constant and the universe is going to continue to expand ever faster, ultimately headed towards Heat Death.
If it’s less than -1 (what’s called phantom dark energy), then the amount of energy somehow increases over time and we’re looking at the Big Rip scenario — the universe will eventually expand so fast that I’ll rip everything apart, even atoms. There’s some fun stuff that might happen if that’s the case, like boiling into a new big bang when trying to rip apart quarks (only works if there’s a lower matter energy state, I think), but that’s another topic and it’s highly speculative anyway.
And if it’s between -1 and 0, it means that dark energy decreases over time, and the expansion is going to slow down and eventually reverse, leading to a Big Crunch, and possibly Big Bounce, implying that the universe “beats” like a heart.
You can google Heat Death, Big Rip and Big Crunch to learn more.
Now, what the paper is suggesting (I think, I haven’t found/received the original paper yet to read it in full) is that recent JWST observations might turn out to be a piece of further evidence that the cosmological constant might not actually be constant, but more like some parameter that can change over time and space. That would kinda lower the importance of w, since the constant becomes parametrized and the “fate” can change in the future regardless. But it doesn’t remove dark energy in any way (it’s a phenomenon that demonstrably exists), just alters our understanding about how the universe operates.
Jeez that turned out to be a long comment. Hopefully my explanation wasn’t too convoluted :)
fearout