Could just be luck of the draw. I’m using the same setup and sometimes I get it, sometimes I don’t

Leather is basically cellulose from animal skins

There are many other sources of cellulose from [mushrooms](Are Mushrooms the Future of Alternative Leather? https://www.nytimes.com/2022/12/14/business/leather-fake-mycelium-mushrooms-fashion.html) to cacti to even pineapple

These are still fairly young materials and aren’t super common. You’re starting to see them more often but usually in smaller runs of more expensive brands. I personally haven’t bought any of these alternative leathers but next time I need to buy shoes I’m going to look into them again