“Domineering Sound Wave”
Because transmigrators' souls had a different wavelength and space-time attribute due to their origin compared to those of the natives, the scanner worked well to distinguish people's souls.
However, sometimes, natives who awakened the ability related to space and time, even if just fragmented abilities, also changed their souls.
Their souls would carry a hint of space and time distortion, making them unique and different from other natives.
There were cases where the World Union caught the wrong person, not a transmigrator.
Fortunately, after another round of testing, the person was proven to be a native, so the World Union never took the souls of the natives, even if by mistake.
If this happened, maybe other powerful forces out there would have used this case to weaken the influence of the World Union, making the world organization a place full of people with their own evil intentions.