I underpaid my taxes due to faulty estimation by TurboTax and is now being penalized for it by the Federal Government. Where is the accountability?

I paid in full for whatever TurboTax told me was due at the time (~3k) of filing last year and now I'm logging back on to file my taxes for this year and I'm being told JUST NOW I underpaid by $87.  I can't even just go through TurboTax to resolve it, and as I'm filing they are just prompting me to pay taxes not even calculated yet to "avoid underpayment this year."  Literally what?  Also having to pay for Customer Service is absolutely abhorrent.  TurboTax is ass