Adding to the last guys point it can be assumed that the general public didn't know that nomus were genetical abominations after all most villains have mutation quirk and the nomus looked different enough that one could assume they were just a gang of villains that looked slightly similar, but if an army of archetypically similar monsters suddenly pops out of the ground with no explanation the heroes will have to tell the truth that thousands of people were being abducted to create these monsters with no notice from the heroes.

TL;DR it's less that there are more monsters now and more that said amount of monsters are made from random civilians who went missing with no fanfare.

It's creepy how cute this is.