App without internet access use internet data

  1. The application does NOT have any permissions
    (0 permissions, no permission for internet access)
  2. In the system setting i turn off wifi, cellular and background DATA for Notally app immediately after installation

After a week of use, I notice that the application also runs the background and consumes internet data (73.73MB) see screenshot.
HOW IS THIS POSSIBLE ?

This app https://github.com/OmGodse/Notally

I report issue https://github.com/OmGodse/Notally/issues/23#issue-660630293

App version: 2.5
Android version: 10


As already discussed on GitHub, this is an application-specific problem. So I doubt that this forum is the right place to investigate this.

Not-so-easy possibility to check this: According to your screenshot, your WiFi is used for data. Thus, one way to see the network traffic would be to set up monitoring on your router, e.g., by logging the traffic with tcpdump and piping it to Wireshark.

i mean if its really does not need net just install firewall (not remember the name now sorry) and cut it down