Why is ‘General” under ’System Services’ using excessive cellular data?

I’m using iPhone 15ProMax at iOS 18.3.2 on Roaming, and System Service General eats up over 5GB of roaming data. Tried the support app, it’s just recommend update to 18.4

i have updated and the problem still persist.

Same problem with iOS 9 user decades ago, and here we are facing the same problem in 2025

at 18.3.2(Roaming) eats up half of my 10GB plan

At 18.4 eats up over 700MB over 1.1GB

what is this general system doing. It does not behave that way in my wife’s phone.

[Edited by Moderator]