sanctions cards are configured with a negative value so sanctions cards actually increase the target's income. On turn 18 an AI played a sanctions card on me, which was a mistake since they were helping an enemy by doing this. Sanctions cards with negative value should be played on allies or self. (This AI had stupidly taken enough bonuses with negative value so their income was 0 so playing it on themselves wouldn't have helped. Playing on self or discarding would still be better than helping an enemy.)
This isn't the biggest dumb thing the AI does, but unlike most AI problems it should be easy to fix.