Hello @emil! Thank you for taking an interest in trying out Coinbase APIs. For the details regarding your concern, we will check on this for you with our team. We will get back to you once we have more information. Keep in touch!
The network parameter was added to support multichain withdrawals, but is only applicable for ETH, MATIC, and USDC on Polygon, and USDC on Solana. If you are transferring any network via the default network (for USDT, this is the ethereum network) then you do not need to use the network parameter in your call.