It seems you may have accidentally attacked the zombitons! The Vilmonicouncil recommends against this. There are MANY things you can do to deal with the zombs. Check the tool, item, and task descriptions for hints, or get help on the Vilmonic Discord https://discord.gg/vilmonic
Unless you enjoy the chaos of a zomb infestation, or if you are trying to balance a zomb-carnivorous-animatroid ecosystem, don't ever attack the zombitons. If this happens by accident, try playing with them with their favorite toy - spoiler: blow bubbles! This will quickly calm their swarming instinct.