What was wrong? Turbo Tax is a self prepared return. It has no way of knowing or checking that you entered something wrong or in the wrong place or entered something twice Or left something out. It doesn't check against any outside sources. The IRS has copies of all the W2s and 1099s your employer and banks/brokers, etc. sent in to match against. Turbo Tax only checks the calculations of what you entered. It is your responsibility to check it over before you file. They only Guarantee that the calculations are right based on the entries you made.
A lot of people made mistakes on their 2020 and 2021 returns ---the mistakes were very often with the recovery rebate credit for the stimulus money. The IRS had to correct the return and often reduced refunds or the people ended up even owing because of their mistakes. The IRS would have sent a letter explaining the change made to the refund.
TurboTax provides do-it-yourself tax software. TurboTax guarantees the calculations done by its software. The information entered into that software is data entered by you, the user. TurboTax cannot and does not check that information against any outside sources, so TT cannot know if you entered your information completely or correctly. It is up to you to enter all of your information correctly and completely, and to check your tax return before you file it. If you forget to enter some income, or enter it incorrectly, enter it in the wrong place, etc. then you may end up owing additional tax to the IRS and/or state. TurboTax does not pay the additional tax you owe. If TurboTax’s calculations were incorrect, and you owe penalties and/or interest, then TT will pay the penalties and interest. The tax due is always owed by you, and must be paid by you.
If you need to enter a claim for the accuracy guarantee:
TurboTax has a 100% Accurate Calculation Guarantee where if there was a calculation error on the tax return they will pay any penalties and interest caused by the error, but not any taxes owed. TurboTax will not pay for a user error or any user omissions of income.
See this TurboTax support FAQ to submit a claim - https://ttlc.intuit.com/turbotax-support/en-us/help-article/intuit-account-billing/submit-claim-turbotax-100-accurate-calculation-100/L88SYklBL_US_en_US?uid=lvr5p2gs