According to Briclot, at one point there was consideration given to the idea of finding an entire civilization living inside the Quantum Realm.
While the Quantum realm is an important part of the plot Ant-Man and the Wasp, we don’t actually see that much of it, but it’s possible that wasn’t always the case.
However, what’s potentially more interesting than the look itself, is what inspired it.
Recently, artist Aleksi Briclot revealed some of his concept work for Ant-Man and the Wasp which showed a very different version of what Janet Van Dyne would look like when we met her near the end of the film.