This is an audio story from Techtsp.com

Instagram has silently rolled out a new feature that some users might find annoying: Instagram Message Reminders. An app that sends reminders to check missed or unread messages is not new. Some messenger apps like Skype send reminders to users who have not opened incoming messages.

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Instagram now has a new, similar feature, at least on Android. These reminders come as a notification, similar to any other notifications, including direct messages. However, the only difference is even if you cleared an original notification without responding to a message, Instagram will still send you another notification after a period.
We received this new reminder notification around 23 hours after receiving the first (original message) notification.
Instagram Message Reminders are not the same as standard notifications that will not go away even after clearing them or reappear along with other unread messages. These are new notifications altogether. Instagram has also added a way to turn off these reminders inside app settings.