Vandami Bhante
Not very familiar with Windows, not using it personally for a long time, I can only provide some guesses what might help a little bit.
1. Opening the task manager (right click on task bar, then "Task Manager", was how it worked in old Windows versions that I remember), one can see a list of all running processes/programs. Many unknown and mysterious usually. One could try just ending this and that process, blindly, without knowing which one is causing the network traffic.
Not reliable. Some mysterious programs running in the background will just restart.
One mysterious always suspicious seeming process I remember is "svchost.exe", often appearing multiple times. Not sure what it is doing, but I have read explanations that it can cause high traffic usage and that that is "normal".
Possibly this built-in traffic eater and possible spy can be shut down.
2. There is a program called "TCPView" for Windows, which can be downloaded directly from Microsoft with no serious strings that I can see, from here:
https://docs.microsoft.com/en-us/sysinternals/downloads/tcpviewI have downloaded it and can send it by email.
With this program, processes are listed similarly as in the Task Manager, but with information on network connections they are using. I think one can also terminate processes from there, similar as in the Task Manager.
3. A simple "solution" might be to just disconnect the Wifi connection as long as not consciously using any internet traffic oneself. So for example just disconnect while writing a long forum post, or recording audio, and then reconnecting again to send it. In that way, maybe not so much traffic will be leeched off by parasite programs (which Windows probably has some built in).
4. The Windows firewall (I think there should be such a thing by default) should have some settings and is exactly for the purpose of denying unwanted network traffic. But I am not familiar with it. Too long ago, and not sure if possible to block with it parasitic traffic that is built into the base system.