iPhone messages showing read even though I've never read them
I got an iPhone 11 in November last year, yet recently, whenever someone sends in a message through iMessage, it'll show up as read even though I've never opened the message before and have never received a notification about the message. Or, it would show up as unread yet I wouldn't get a notification. However, iMessage works perfectly fine on my MacBook. This only started happening a few days ago, and I'm worried maybe someone has hacked into my phone? Does anyone know what's happening? Thanks!
iPhone 11, iOS 13