How do I clean the rubbery non stick bottom surface of my new bathtub?

Have you tried sprinkling good ol’ baking soda on the tub and scrubbing with a damp cloth or brush? Whenever my store-bought products fail me, I always give it a shot. It rarely fails me. Best of luck!

When we had our new tub installed we were told to use Clorox bleach spray cleaner on our tub. We have had it now for over 16 years and still looks as good as the day it was installed.

I use this as a safe alternative to bleach. It’s amazing how well it removes things from surfaces like this. I’ve used it on the non stick bottom of our bathtub in our old house. It’s worth a try! https://chemistrycachet.com/the-best-way-to-remove-mold-mildew/

It seems that a mixture of Dawn and Comet did the trick for someone with that type of bathtub. Here is more info on that https://www.houzz.com/discussions/2278463/cleaning-non-slip-surface-in-tub

Try using MR CLEAN SCRUB PADS with Clorox sprayed on

I use Toilet Bowl Cleaner and rub it into the strips with a brush, let it set a while. I left mine overnight. It cleaned the strips for me.