Elegran
I use a waffle-weave cotton teatowel, one of several which I bought years ago but discarded as not being as good for drying dishes as the linen ones. Once it is wet it clings to the shower base and doesn't slide around. After the shower it gets wrung out and hung over the grab rail, and it is washed with the towels - having several means there is no pause while the washed one dries.. It never gets dirty-looking or mouldy.
Same here, we bought them in Madeira some years ago and they’re very useful, much easier as well than trying to keep a rubber mat mould free, they are always a nightmare.