Delayed incoming iMessage messages

I have an iPhone XS and for the past year there have been occasions, maybe about 2-3 times a month, that I don't receive messages from people until hours later, or even days later, OR they won't come in until I restart my phone, even then sometimes they still won't appear until later.

My messages to others say delivered but it's just weird that they'll reply and I won't even know because the messages themselves won't pop up in our conversation, or I'll get no notifications/app badges whatsoever until way later.

I'm tired of having to restart my phone because I'm worried I might've missed someone's message. Help!