Mutinous soldiers in Sardinia killed the Carthaginians there. When Carthage prepared an expedition to recover the island, Rome declared that the preparation would count as an act of war. Rome then demanded the cession of Sardinia and Corsica. The resulting addition to the settlement belongs to 237 BC, after the Mercenary War, rather than the original peace of 241 BC. Polybius judged this Roman action unjust.
Notable Point · 2:11:06-2:12:26
Why Carthage lost Sardinia and Corsica after the peace
Rome used the threat of renewed war to take Sardinia and Corsica while Carthage dealt with the consequences of mutiny.