Why is it that if you turn off mobile data transfer in Android, then money for insignificant traffic is still withdrawn?

Question

Android

Why if you turn off mobile traffic, then 3G is still turned on, and a fee is charged. I noticed such a thing, maybe it's because of Google Maps which periodically asks: "How do you like this place?" If you left this or that store, having lost your Wi-Fi connection. Maybe it has something to do with the google maps app and GPS settings?

Tried to reset to factory settings, still the same situation.

This is very noticeable, because I charge 2 dollars for a daily Internet package, only when you use it, the connection fee is charged, any connection, and then 500 mb per day are charged. After checking in the billing statistics, a few kilobytes appear there. If you turn off the phone, and thereby do not go online, then the money is not withdrawn from the account. Therefore, the operator-provider has nothing to do with it.

Android 8.0 is not rooted, applications are kept to a minimum.

Can someone come across?