Well spotted! I'm not familiar with trading accounts or blockchain.com, but maybe worth checking whether there's also a 'funding account' or anything like that which allows you to actually withdraw funds?
Blockchain.com trading account works like an exchange and you can trade bitcoin and some other cryptocurrencies there.
In blockhchain.com, there is no funding account or something like that. If you have verified your identity, you should be able to withdraw your fund from your trading account to your main wallet or any address you want.