The BTC has landed in my wallet, thanks for your concern, but I don't know why the transaction take this long before confirmation.
Is it because I decided to send it to an exchange wallet in order to avoid the network congestion then?
All good, the transaction was broadcasted since yesterday but probably network fees increased before it was confirmed and only came back down today, that's why it took longer to reach your exchange wallet.
Next time I suggest you look the withdraw address up in an explorer to check yourself if the transaction was broadcasted or not.
We also highly recommended that you first withdraw from Whirlwind to one of your own addresses and only afterwards send where you want to. This way even if the withdraw from our multi-sig gets stuck like it happened this time you can still spend the UTXO with a higher fee and that will confirm the transaction faster.