There is a programming error in how Turbotax calculates the mortgage deduction when refinancing in 2020, and the sum of the old and new mortgages are more than $750,000. It adds both old and new Outstanding Mortgage Principles and limits the deduction accordingly. For example if both old and refinanced mortgages are 750,000, it will add both to 1,500,000 and limit the deduction to half what it should be. After hours of search I found a workaround, but I think the program need to be fixed since many users don't know about that and end up paying more tax than they should.
The workaround is:
https://ttlc.intuit.com/community/loans/help/what-do-i-do-if-i-have-multiple-1098s-from-refinancing-...
