Dark energy simply won't work correctly to explain expansion.
In 5 billion years we will collide with andromeda galaxy, how is that possible in a universe expanding from dark energy?
Here is a couple of good reasons to think of it as an illusion or reality for different reasons.
Our Big Bang exceeded C speed at the start so most of the mass of our Big Bang is beyond the visible universe we see, we are simply being pulled to a location of more mass.
Our Big Bang is just 1 in an endless sea of quantum fluctuation that is the real endless universe, the influence of all the other infinite Big Bangs now has more gravitational influence on us than our own Big Bang has on it's own region.
Our Big Bang is a separate universe but endless numbers of them exist, gravity can interact between them all and our universe is simply moving faster towards the infinite mass of all the other universes.
Assuming you mean expansion, then another explanation for redshift would be required. This was given strong consideration in the past, and you can look-up “tired light” to learn of its merits. But it was debunked.
Also, and in support of redshift values, is the delay found in Type 1a SN. if a very distant supernova is observed, then per expansion, it’s brightness will take more time to fade.