Reminder Notification after Do No Disturb mode

[Android Central Question]

Whenever I have received a WhatsApp message during my do not disturb time (23:00-08:00), my phone will make the notification sound around 15 minutes after the period has ended (not on the dot, just now it was at 08:22). It's highly annoying, but I can't find where to turn this off. Neither the phone settings or WhatsApp show an option that causes this. I have reminder notifications turned off. How can I disable this?