Windows 8.1 is subject to the following .....
Microsoft will download to your computer a copy of Win10 as a "just in case".
They are also including Win10 as a "recommended" update so when Windows update runs it will download again.
There have been some updates for Win7,8 and 8.1 that cause some "behavioral" changes to those Operating Systems that cause them to emulate some of the "features" found in Win10 ... namely the collection of data from your computer that is then "shared" with other ...."partners" of Microsoft.
This collection and sharing will use data that you didn't use in the past as well as the background downloads of Win10 in both forms .... "just in case" and "recommended update.
The list of "troublesome updates" (known as KB's) is very long and likely beyond your ability to safely remove.
The fact is that Microsoft has .... changed directions and as such so has Windows as we knew it and that includes some effects to the current Microsoft operating systems.
Frankly I'm at a loss as to how to advise you .....
Your daily allowance is very limited
Windows has turned into a nightmare for those with limited computer experience and data caps.
You COULD set Win Update to NEVER which would stop further data bleeds but would leave your system vulnerable.
I have been around computers since .. there have been computers. I have totally disabled Windows Update on all but one of my eleven computers since November of 2015 and I spend a lot of time carefully researching and removing a number of reoccurring updates on the one computer that is allowed to update.
Please note that I am not advocating that you totally disable Windows Update.
