I do find it strange that your vet did not 1) consider pooping/peeing a hormone-related behavior and 2) doesn’t seem to present spaying as something to do (based on your short mention)?
If there’s intent to go in a certain place or on a certain object, it mainly revolves around hormonal behaviors, such as marking territory or asserting dominance. Both these behaviors are significantly reduced through spaying/neutering a rabbit, as these reproductive organs are the source of hormone production and regulation.
Has your vet discussed spaying your rabbit in general?
Outside of spaying, the most direct method would be blocking off the kitchen and seeing how that is tolerated by her. If she’s decided that’s a place she loves to mark, it’s difficult to change a rabbit’s mind on that. Would that be plausible?
The answers provided in this discussion are for general guideline purposes only. The information is not intended to diagnose or treat your pet. Seek the advice of your veterinarian or a qualified behaviorist.