What could be causing high cellular data usage on my iPhone?

My cell provider is Verizon. I have a shared data play for 2GB (unused data is carried over to the next cycle). For decades this has been all my wife & I need. A few months back, I got a notice that I was about to exceed my allotted data. I tried to get some more detailed info from Verizon about what was using the data, but they were less than helpful. I ended up buying an extra GB. Today, while checking my cell account, I find that I have used 53% of my data half way into the billing cycle. When I checked further, I see that 69% was used for web, 15% for social apps with single digits for remaining categories. Of those single digits, games was listed at 4%. This is troubling since I have game center turned off and always have done so. I do admit that FaceTime & Apple News are used repeatedly during the day, but with using my home wifi network. Very, very little used when out and about. I have only apps I would need (banking, gas) associated with cellular use and they are turned off when not being used. I have app refresh turned off. This past week I have added Sirius/XM app to iphone and use with apple carplay and I am in the process of deciding whether an upgrade in data is warranted. The big question: what could be using so much cellular data via the web? Seems the concern started since the upgrading to iOS 18, but that may be the boogieman talking.

[Re-Titled by Moderator]