Windows 10, no firewall other than Windows Defender.

I can't say what triggers it, but every now and then I gotta "update" the game even though the last patch was weeks ago.
Every time this happens I'm hoping there was an actual patch, until I see it's downloading 4.7 gigs of files...
I used to play without steam and now I run the game through Steam, and in both methods this happens all the same.
I know for a fact that an instance of the game isn't running when this happens, because A) I made sure, many times (this isn't a new issue for me), B) Sometimes happens on the 1st launch after a PC restart.
Running the client "As Admin" also didn't seem to change anything (had it automatically on the shortcut for a while)

Anything I can do about it?