from what i found arbeth is in the ethereum network so I thought it counted as ethereum because i found that arb are layer 2 ethereum
i have usdt on tether ethereum network
Yes, if it's arb, it's still not ETH. You need ETH to proceed with your swap and that is because ETH will serve as your gas fee.
So, to understand it easily.
ETH = gas fee
ARB =! ETH