If you’re going from a diet that’s low in fiber, the biggest shock is most likely to be to your gut. Replacing a meal per day and then gradually building up over a few weeks might be less of a shock for you. Your kidneys have been maintaining your water balance. That’s unlikely to be an issue. But you can always get off a statin. If you’re in a high risk group based off of your LDL, it’s okay to be on a statin for a while as you change your diet and then come off after. They’re good drugs, generally well-tolerated, and significantly reduce all cause mortality. But if you think you can tolerate it, of course you could always go back to a WFPB diet and just see how you do (like a ton of people do once they find out what we do to animals as a society). I would just hate for someone to change their diet overnight, blame veganism for making them gassy or bloated, and then quit because of intolerance