Perhaps in the past you were using the Simplified Method (correctly or incorrectly) to calculate the taxable amount of the pension. Examine the bottom of TurboTax's 1099-R form for this pension in your 2019 tax file to see if the Simplified Method was being used.
The Simplified Method is to be used only if you made after-tax payments into the pension, and the Form 1099-R has box 2b Taxable amount not determined marked or you know that the amount reported in box 2a is incorrect.
Also, if tax withholding is different from what you assumed on the old Form 1099-R that will change your refund or balance due.
And as macuser_22 said, make sure that you only have the old, transferred-in form or the newly entered form present, not both.
