Cotton has a very prominent ecology impacts like the insane amount of water required, and the associated agrochemical runoff that includes nitrates, poisons (especially pesticides) making its way back into the water system.

https://www.worldwildlife.org/industries/cotton

The only mass scaled alternative is synthetics made from oil.

Until a sustainable alternative reaches scale. This is lip service for vegans.

Wait until you find out the only alternative is copious amounts oil products