Message notification stays even after I read the message.

I am new to iPhone and I noticed that I will have multiple Instagram notifications in my notification center even after I read the messages. After I go to the app and read all my messages, the notifications are still in the notification center. If I open a message notification, but there were multiple messages sent to me from the same person, only one of the notifications would leave but the others stay.

My android would clear the message notification as soon as I open the individual chat and read the message, it helped prevent the hassle of manually clearing my notifications and prevents them from piling up.

Is this just a downside faced when switching to iPhone, or is this just a bug or feature I can change in settings?