[NFP] 1.0.8.4 Capturing Vampire Castle

[ferenginar]

I started a game as America, Bull Moose Roosevelt. Picking Hermetic order as the Secret Society, with their ley lines, thermal fissures and quite a lot of mountains, I got some very nice +6 +7 campuses. Went to war with Greece, then Khmer. Noticed something very odd and quite unexpected. Khmer was the Sanguine Pact, and when I conquered them, I kept their Vampire Castles, even after wiping them out.

Is this a bug, or intentional? I don't know, I'm usually playing the Sanguine pack, the food and production from those castles is insane.

https://forums.civfanatics.com/media/20210121184026_1.6399/full