Isn't VAR supposed to be used to check straight red offences anyway?
Well yes, but it's supposed to be used to look all offences and if they meet the criteria laid down AND constitute a 'clear error' they can be reviewed with a view to being changed. Included in the category of incidents eligible for review are straight red cards (and not, for instance second yellows) but it still must "only be used to correct clear errors."
They're not supposed to just look at all red cards or potential red cards and then go to a review if they think they might be able to find some grounds to change the referee's decision - they should only be reviewed if there's evidence a clear error has occurred.
This is one of the main areas where I think VAR is falling down - referees and VAR's seem to be going straight to a full review every time there's a goal, penalty, potential red card etc, whether there's evidence of a clear error or not. For me, the Tottenham vs Rochdale game was a classic example of this - it seemed as though every major incident was going to a full review, despite the protocol saying that's not what's supposed to happen.
Here's a paragraph taken straight from the VAR protocol summary:
The aim of the experiment is NOT to achieve 100% accuracy for all decisions as there is no desire to destroy the essential flow and emotions of football which result from the game’s almost non-stop action and the general absence of lengthy stoppages.
I would say that this is exactly what is happening - too many lengthy stoppages and a serious erosion if not destruction of the "essential flow and emotions of football."
If the requirement to meet the principles of the paragraph above is the measure of VAR's success, I would have to say that from what I've seen of it, it is a notable failure.