According to news on December 20, LayerZero started voting on the proposal "whether to activate the LayerZero protocol fee switch". This proposal will determine whether LayerZero starts charging protocol fees for each message. The protocol fees collected will be used to buy back and destroy ZRO, reducing its circulation. Messages between Arbitrum and Optimism currently cost a $0.01 DVN/executor fee. An additional $0.01 agreement fee will be charged after the proposal is approved, bringing the total cost to $0.02. The protocol fee of $0.01 is charged in the funding contract, which will automatically buy back and destroy ZRO.