Is the ref not clearly giving offside in the clip? Other channels appear to have called it but Sky just ignored it and wanted to cause controversy. As an aside, WTF is Mica on nowadays.... Did they all (and some on here) get selective blindness? Watch the clip. Ref listens in his ear piece and gives offside...
The offside is for the offence after the 'handball'. At least that is what has been explained to me and it makes sense. That leaves the question, "was it handball?" And to judge that you need a still of the incident and then you need to refer to the FA rules and the pictorial diagram which explains the regions of the arm which are regarded as 'handball' territory.
The ball strikes Rodri's arm right on the border between the upper arm / shoulder area, and lower arm and so the VAR official can not deem it an obvious error by the ref. It's a borderline decision.