Honestly, if seduction and stuff was that easy to just have for a noble, defenses against it should be part of the basic kit of every noble and royal family.
I was gonna say the same thing. Even if it’s an incredibly rare and expensive drug that most nobles couldn’t get, half the country’s budget should be going into ensuring that the king and other royals can’t get brainwashed
Amusing that its public knowledge that charm potions exist, or that its even possible in the first place. ( because magic )
They could be the inventor of said potion and nobody knows they are even a thing.
But if it is a known thing and there are ways to counter it, then yes....
There really should be some kind of way to deal with it.
I read another manga recently that had Isekai vampires ( which mind control / charm powers. )
But because almost nobody knew vampires were a real thing, only the MC found out about it after being charmed.
( they were basically a myth just like in our real world until a random Uber mage use necromancy to become one in that story)
So the only reason the vampire did not permanently charm the king and queen was because of the MC called them out on it.