[2023] [1.7.0] Plague of Rats ability works only in Siege of Paris DLC

I don't know how many users noticed this, but the Plague of Rats ability is useless in any other part, except Francia. You can't use it even in River Raids (Rhine). I mean, yeah, you can activate it, but it doesn't kill/harm anybody, except the Siege of Paris DLC. Is this a bug or a feature, like the Rune Forge one?!