Lollo used to do this to my trouser legs before he was neutered, and it was a prelude to him trying to hump me. i ended up having to roll up my trousers when he was out and about (try explaining to guests why you look like you’re going for a paddle in the sea!!) He doesn’t do it much now, just very occasionally, (and only the scratching not the humping) but he does scratch the rug/carpet/curtains. Blue is very much a scratcher, in her litter-box, with cardboard and on the plastic floor of her cage but not with fabrics. i don’t know why either but there would seem to be a bunny to bunny preference for things to be scratched.
i guess to stop her scratching you though, you’ll have to ‘remove’ her from you each time she does it and maybe try to set up a key word that she can associate with you telling her to stop doing that particular thing, so eventually you just say the word and she knows you dont want her to scratch.