What is downloadfile.bin? At random times, Download manager start downloading series of files named as downlaodfile.bin, downloadfile-1.bin and so on. 

I got this issue since today morning. And it happened twice today.

What is this file and why it is getting downloaded? Thanks.

Device information

Device: Moto G4+
Android version: 7.0 Nougat


Screenshot (click for larger variant)
I use Moto G3 with Lineage OS (July month build). I had the same issue of auto downloading which started two days ago. 

What I have observed is the downloading takes place when I turn on mobile data after 10 AM in morning or 10 PM at night. The files are not shown in ES Explorer app, but I can see those files queued  if I use in-built file manager of Lineage OS. I tried to see which app was using mobile data at that time using My Data Manager app and it showed that Media Storage system app was using the internet.