Turbo tax figured my tax wrong

[42Chunga]

2024 tax year. I have usually only have SS benefits plus interest income and don't pay have to pay taxes. For 2024 I also had capital gains (which were imported in so are correct). Turbo tax said I owed $583. I wrote a check. Recently I received a letter from the IRS stating I owed an additional$3,134.12 which includes $70.12 interest. I got an IRS agent on the phone (a minor miracle) and he reran my taxes and said turbo tax in wrong. I wrote another check.

So what gives? If I can't get an explanation as to this discrepancy then I can't trust Intuit and will never buy any of their products again (as well as leaving crappy reviews where ever I can).

[Bsch4477]

What were the amounts of your proceeds and cost basis on your return?