Fees, as measured by median gas prices, spiked to as high as 270 gwei late on Thursday, temporarily touching a level last seen in June 2022. That pushed up costs of trading swaps to anywhere from $60 to $100 for a few hours. Gwei is a small unit of ether (ETH) equal to one-billionth of an ETH and is used to denominate gas prices. Gas refers to the fees Ethereum users pay to ensure their transactions are included in the earliest block by network validators.