I don't know what people are whining about.
What's this about cliches? It has the otome frame, but before that, our MC is unusual and unique as fuck. The absurd superwoman who people don't think will die upon being poisoned. That's utterly hilarious. Moreover, her brain seems to be wired in a way that's practically insane, and her response to the prince acting like a dipshit is "I've lost interest."
Not even mentioning the 20 year timeskip. You certainly never see those.
That aside...wow. The poisoning is...well, that's about as brazen as can be, right? What sort of excuses can even be given, since it's been clearly announced that the heroine prepared the poison and the prince made it clear that he knew about it. Unless one of the followers takes the fall, I guess.