Unofficial Factorio 2.1 compatibility fork of Mylon's Pollution is the Solution (https://mods.factorio.com/mod/Pollution_is_the_Solution), licensed MIT same as the original. No code changes were needed beyond declaring 2.1 compatibility. Retire this fork once the original mod supports 2.1. Pollution kills biter nests. After spawning 60 biters via absorbing pollution, they die. Biter farms should not be affected.
Small changes concerning balance, gameplay, or graphics.