Nerf adult Dionaea, somewhat.
Created by: Jeroen52
So I was reading through some code looking to fix some typos or something, and I noticed that no race is breathing carbon dioxide. What about nerfing the Dionaea's regenerative power a little bit. Make them able to consume carbon dioxide when it is dark or badly lit, they'll slowly produce pure oxygen from said carbon dioxide.
Edit: Sauce that no race uses CO2: https://github.com/d3athrow/vgstation13/blob/157b46a6dae069337ebd8bf65bc2f756be0cae70/code/_onclick/hud/screen_objects.dm#L369