Just like I said on this thread:
I am having an issue in swapping and transferring OP. When i try to swap the OP to the USDT, the below error message appears. Even though i have enough ETH in my Unstoppable wallet, yet it says the eth balance is low, while i have more than 1000$ of ETH balance in my wallet.
Optimism (OP) is layer 2.
The fee is not ERC20 ether, but ether on Optimism network.
Search for ETH on Unstoppable wallet, you will see ETH (Optimism). That is the ether that you will use for the transaction. On exchanges and onchain transfer, the ether transaction fee on Optimism network is very cheap. So buy it should not be a problem.
Not ether on Ethereum network that you need for it, you need ether on Optimism network for such transaction.