Why is my iPhone 15 not getting full network bars?

I never have full bars and sometimes pages won’t load or safari can’t connect to browser. In order to get any good service I have to use my home WiFi and it’s causing my internet to come very close to going over my monthly allotment which will

cosy me $10 more month every-time it does. Even when WiFi is on I still only have 2 network bars. Is anyone else having any similar issues. I see the iPhone pro max had similar issues. And what can be done about this.

[Re-Titled by Moderator]