An example is the Native Farms - when you stake your ProtoFi LPs in the farm, Harvest your ELCT or withdraw your ProtoFi LPs, you will have to pay a transaction cost. The cost depends on the complexity of the Smart Contract process/logic, however, you will always be able to review the proposed transaction and costs in advance, before approving it. If you are using MetaMask - a transaction window should be displayed in your browser, every time a transaction has to be processed.