Differences in chain design inevitably lead to some unique chain-specific considerations. Below are idiosyncrasies we have identified, though it may not be comprehensive and we are interested in hearing if you encounter others.
Gas prices on Avalanche mainnet are often underestimated when getting type 0 estimates (e.g. for the providerRecommendedGasPrice strategy). The error manifests as the maxFeePerGas being set to less than the block baseFeePerGas, resulting in unfulfilled requests. A solution to this is to set recommendedGasPriceMultiplier to slightly greater than 1 e.g. 1.1.
Execution costs on Arbitrum are calculated slightly differently than Ethereum, which impacts the gas required to fulfill requests. To account for this, it is recommended to use a minimum value of 5000000 for fulfillmentGasLimit when using both Arbitrum mainnet and testnet. Note that fulfillmentGasLimit is optional, so if it is not specified, Airnode will attempt to estimate the appropriate gas limit automatically. Read more about ArbGas gas and fees.
On the Metis testnet Stardust, though not on the Metis mainnet Andromeda, it is recommended to use a fulfillmentGasLimit of at least 5000000. Note that fulfillmentGasLimit is optional, so if it is not specified, Airnode will attempt to estimate the appropriate gas limit automatically.
Using type 0 transaction types is recommended over type 2 so the use of providerRecommendedEip1559GasPrice is discouraged.
As a L2 scaling solution, Optimism has an L1 data fee and an L2 execution fee, which are accounted for separately. To cover the L1 data fee when a sponsor requests a withdrawal, an amount has to be subtracted from the funds returned to the sponsor. The withdrawalRemainder parameter has been introduced specifically for this reason, though the value required will differ between Optimism mainnet and testnet due to differences in L1 gas fees. For Optimism testnet, a withdrawalRemainder of 1 gwei should suffice, while for Optimism mainnet, a value as high as 2.4 finney (2400000 gwei) may be required in order to cover an L1 gas price of 300 gwei and 8000 L1 gas used by the transaction.