The refund shown on your 2018 state tax return is not necessarily the refund you receive from the state. States often make adjustments to refunds resulting in a different amount than shown on your tax return. If TurboTax automatically entered it, the amount would sometimes be wrong.
Not sure why TurboTax would not know that you didn't itemize deductions in the previous year if you transferred last years information before you started your 2019 tax return.
