I've never discussed this with other women (well, because I've never assumed that anyone would masturbate in a public bathroom - naive little me), but I'm like 99 % sure no woman does that. A public bathroom is literally one of the least sexually appealing places I can think of.
and even if they do (which they 100% do not) why does that mean the male sex class, the sex class that commits 99% of sexual offences, is suddenly allowed into women's spaces? it makes no sense.
Public bathrooms are gross enough to use for their intended purpose.
I think it's extremely safe to say that women don't masturbate in public restrooms.
I saw several comments on Twitter recently that ‘cis women masturbate in public lavatories all the time’. Quite honestly I think they’d seen some porn vids filmed in public loos and took them as documentaries.