Hey Sean! 😊
This cannot be disabled, as it has a fundamental role: prevent that you forget your login code!
The app will ask from time to time to enter the login code even when you have the fingerprint set up. That way, should the fingerprint not work for any reason (or should you need to log in from a different device), you'll remember your login code. I'm sure that if we never asked it, we'd all forget it in no time 😜
Of course, this also helps to raise the security of your bunq account 👌