Does a large state refund affect federal taxes negatively due to SALT?

I have a tendency to roll over state (and federal) tax refunds into estimated taxes as a way of absolutely preventing surprises at tax filing time.

 

I wonder if too big a state refund negatively affects federal taxes given the $10,000 SALT limitation?

 

Specifically, is the SALT amount based solely on taxes actually owed rather than involving the refund?

 

Or is it a big mistake to defer a big refund?  (Yes, I know the arguments about giving the government a free loan...)