Mini-Realm's Name
Davis and the others got inside Stella's mini-realm.
Stella came flying over before Davis caught her and caressed her head roughly, chastising her that she was going overboard with Zenova Artoria when she suppressed her. From what he had seen, Zenova Artoria was almost as powerful as Stella, capable of defeating her if she went all out.
So if Zenova Artoria decided to counterattack, then the mini-realm would've been exposed as a broken mini-realm would've emitted spatial undulations into the world.
It was a dangerous moment.
This was only a small mini-realm and not a huge mini-realm, so its defenses were weaker than what a huge mini-realm would have but then again, creating a huge mini-realm would take more time, perhaps thousands of years.
That's the sort of environment Stella grew up in; the Void Dust Secret Realm.