Meta-owned Instagram launched the ‘Quiet Mode’ to discourage people from consistently being on the app. Targeted at teenagers, the ‘Quiet Mode’ will ensure that once enabled, they do not receive any notifications.
Once a user enables the Quiet Mode, the profile activity status will change to 'In Quiet Mode' for the followers. If someone sends a Direct Message while the user is 'In Quiet Mode', Instagram will send an auto-reply (just like the automated reply that are sent by WhatsApp Business users).