System applications: what process is responsible for capturing data usage (mobile / WiFi)?

The problem is that it is broken for me. I customized a lot, specifically installing a firewall that uses root and deactivating the receivers and streaming services in many Huawei and Google applications that were preinstalled. I guess one of these should be responsible for capturing the amount of data that flows through each interface and from which application it originates, since the function was broken.

Which process (on any Android phone, you can probably find the equivalent once you know where to look) is responsible for doing this?