Big business at the moment with a tidy profit I am sure, some of these mats go for £80 !!
https://www.ecowatch.com/eco-friendly-non-toxic-yoga-mat-2297552923.html
Back in the day a bit of old lino with a fibreglass backing would have been fine.
Each to their own and all that, the only thing I don't like is the holy than thou context and attitude some people have and that goes for all backgrounds and opinions.