The enormity of the Mechanical Ark is such that loading billions of beings aboard is not an exaggeration.
And with the modification technology handed down by Waluk, the loyal troops he brought out were all biochemically modified, possessing Insect Race traits. At the very least, they were corrupted and infected by the void, parasitized by insects.
They are precisely the main source of the Subspace Shadow.
Of course, merely over a billion beings are not enough to create such a massive Subspace Shadow. The number of beings aboard Alfonso I accounts for only about 15%-20% of the total.
After all, there's another Mechanical Ark and several hundred ships, some of which are large transport ships recently brought from the rear, intended for Alamita's ground offensive. Combined, from sailors to ground forces to logistics personnel, the total reaches between 5 to 8 billion.