Most clothe seats are synthetic fiber based on oil and nat gas. Like 99.99% of car interiors are synthetic. Because they are cheaper and more fire resistant.

So if you worry about plastic pollution in the oceans et al. you should not want this either.

https://www.ecosourcellc.net/2019/08/08/microfiber-pollution...

https://ecophiles.com/2017/01/31/plasticfiberpollution/

https://www.patagonia.com/stories/an-update-on-microfiber-po...

https://www.oceancleanwash.org/the-issue/