When does Adventure Time: Fionna and Cake return?

The series follows the eponymous Fionna and Cake the Cat, alternate-universe versions of Finn the Human and Jake the Dog. It is a spin-off of the Cartoon Network series Adventure Time (2010–2018) and the third main installment in the Adventure Time franchise. The series also features Simon Petrikov, who for most of Adventure Time had been known as the Ice King.