If you are running your own Bitcoin node, you can check your own node to confirm the withdrawal has been broadcast.
If you are not running your own Bitcoin node, you can scroll down to the "Withdrawal History" tab of your dashboard, locate the completed withdrawal in question and click on the word "completed" as shown below.
You will then be taken to a mempool.space, a public block explorer, that will allow you to confirm that the transaction has been confirmed on the Bitcoin blockchain.
To do this yourself, you can plug in the Bitcoin Transaction ID into the block explorer, and see if the transaction is confirmed on the blockchain.