Microsoft's OneDrive cloud storage service is installed on your PC by default, and it can cause some trouble when playing PC games on multiple devices.
I fell into this trap when I reinstalled Win10 on my PC after I upgraded the hardware. I made the mistake of giving Windows setup my Microsoft login because it seemed like that was the only way forward. That automatically enabled OneDrive sync of my documents folder. Which was bad because I had gigabytes of save game and mod data that I was moving over. I noticed all the disk and internet activity as OneDrive was syncing it. It took a while to fix and there are still side effects in the system.
People keep coming up with new ways to bypass it and MS keeps coming up with new passive-aggressive ways to stop them. They won't just fully say you gotta log in, they have to be sneaky about it.