I wonder if it will correlate to the distance the planets are from the center / settled planets? So the further out into "wild" space you get, the higher the difficulty level.
idk how I feel about them showing the level in the UI, though. Elden Ring has scaled areas but you find out by showing up and then getting wrecked, which adds to the story of your playthrough. with levels being shown in the UI, you can just choose to avoid the higher level places early and lose out on that kind of learning-by-exploring.