i wouldn't worry much about rubber compared to pleather, even real leather, right now i'd try to avoid things with pleather/leather unless it's really small part, although i have few figures that's leather heavy, the Medicom ones still looks ok but can't be touched, once you touch it it starts to peel...
The latest i have that is leather heavy is the Art Figures Dredd, Hardcore leather level pretty much from head to toe are leather, or pleather i really don't know... he looks great but hope it last while it's fun.
I recently fixed up the Medicom Kerberos Panzer Cop, it came with vinyl balaclava (which i peeled off the layer and gave it a black dye, it was original brown fabric in black vinyl coating), pleather inner jacket (which i peeled off the pleather coating), removed all the pleather straps that either disintegrated or broken into half & replaced with Real Leather 0.6mm thickness. Took me 1 hour just to clean them up, another few hours to make the leather straps & put them back on.
Many figures come with pleather that you might not notice until it starts breaking up, like belt, collars, or prints on clothes.
I haven't tested using Plastic Dip sprays to redo the vinyl layers. it seems they can give leather like effects and is flexible.
Medicom Pleather are hopeless even after so many years they couldn't bother to improve, yet they keep releasing pleather heavy figures.