State refunds for 2019 & 2016 on 1099-G causes reduction in Schedule A deductions. Why?

Got a 1099G for state tax refunds for 2019 and 2016. Entered separately. Since we itemized both yrs, these are apparently taxable, but  why does it reduce Sch A deduction for 2020?  (Note that we did pay $1000 w our tax extension for 2019.)  TT says:    
"Because you pd part of you 2019 taxes, in 2020, we will reduce your state tax itemized deduction on Schedule A, Line 5 by $514." 

 

We also sent a payment w our 2016 extension, but it didn't ask about that. 

Thanks for any help.