Current fee levels in wei and gwei (1 gwei = 10^9 wei). Parallax has no EIP-1559 base fee: a transaction pays gas used × gas price, all of it to the miner. Returns the node's eth_gasPrice and, from Parallax's Bitcoin Core-style fee estimator (eth_estimateSmartFee), the price expected to confirm within 1, 3, 6, 36 and 144 blocks (10 minutes to a day) with the estimator's historical success rate for each; "legacy_fallback": true means the estimator had too little data and returned eth_gasPrice instead. Also the cost of a plain 21,000 gas transfer at each level, in LAX.