Type 123 (0x7b) transaction type allows paying for gas in currencies other than the native asset (CELO). It has an additional field feeCurrency which allows the sender to choose the gas currency. See here for details on using fee currencies.The fee currencies available at Mainnet launch will be:
In the Optimism model, an extra fee is added in order to cover the cost of transactions on the L1. This can be surprising to users as it is not included in the results of calling eth_estimateGas and is challenging to predict.The Celo L2 improves upon this experience by always keeping the L1 fee at zero. The L1 costs are covered by raising or lowering the base fee floor. This approach allows the full transaction cost to be estimated ahead of time.
The Celo L2 adds a base fee floor, which imposes a lower limit on the base fee. This is currently configured via the chain config.The starting base fee floor values are:
Celo L2 blocks reference L1 blocks that are finalized, which fully protects against L1 re-orgs. In contrast, Optimism blocks reference only 4 blocks behind the L1 head.
