EXCESSIVE/INACCURATE DATA CONSUMPTION

I just got the Iphone 15 pro max 4 months ago. It is saying I am using more then double every month then my Iphone 12 pro max I had on verizon for 3 Years.... Anyone else having issues? Xfinity Keeps blowing me off after hours on then phone. Apple ran tests on my phone and said everthng is ok and data usage is controlled by the provider.. they are saying I went through 30 gigs in 14 day when my phone says 25 and I never used more then 15GB in a month on verizon. WTH is going on? Spent hours on the phone with someone who has no idea what they are doing, its the 3rd time calling and they told me over a month ago they would call me back in 48 hours. Should have never left verizon