I have turned off all the different factions and just play with regular, explosive, and armored biters.
In my game currently often when a attack dies on my wall the biters will release some kind of purple cloud that damages my walls a little bit. It's incredibly annoying because it lags my game a lot with all the little damage checks.
Could you or anyone tell me how these clouds are generated so I can turn them off?

i managed to remove those clouds
I also removes a ton of unnecessary math and checks for the OnDeath and also removed all on_damage triggers because my game was losing ups. Now my game doesn't lag anymore.
this mod is easily one of the most harmful and unoptimized mods in terms of ups

From what I've seen, fire and clouds put a significant strain on the UPS.
And while I replaced the fire on the biters with my own, I didn't replace the clouds. Unfortunately, while replacing clouds with puddles helps with performance, it greatly reduces the visibility of what's causing damage.

Also, by removing the "on damage" triggers, you've removed the defenses of some biters, significantly weakening them. Furthermore, the "power-up capsule" that was one-shotting Biters will no longer work.

None of that is relevant compared to not lagging your game to death

So even while trying to remove all things related to clouds, they still show up. Can you tell me specifically what is causing some biters to spawn clouds? Is it on death? It is a kind of special attack?

Could you please not ignore my request?
I would like to know what piece of the script is causing the clouds to appear, because they appear during attacks on my thick walls. They cause a constant stream of tiny damages on a large area of a bunch of wall pieces, lagging the game a lot. I would in fact classify this as just a complete performance hog.
If you tell me what does it, I can modify it privately. I'm not even asking you to change the mod or anything.