Is it just me or do you have the same Thing happening? With the todays big Q1 Update, Steam downloads and installs 1 Item then it checks the whole Installation (108 + GB ), downloads the next Item, interrupts the Download, check the whole Installation again .... and so on. That is not normal in my Opinion. And my Internet Connection is stable the whole Time, so no Interruptions on my Side.
I had this issue once on a previous version. There is some kind of Workshop synchronization fail and it redo all the content. It happend twice for me, but at that time i was launching/restarting rF2 a lot of times for testing some workshop items refresh. With new content management it has another weird behavior i think.
In my Case it was the 992 Cup that caused the Problem. The only Thing, that i could imagine as the Reason, is that i was subsrcibed to the 992 Cup @ Nordschleife Hotlap Competition, that i wanted to try out, because it uses my instant Timing Mod and also to see how slow i am. Howsoever, after some Manipulations, where i don't know which one was the deciding one, everything updated properly now.