did you report in Turbotax all the advance economic impact payments that you received?  it looks like the IRS records indicate you got $1800 more than you indicated. you should get a letter of explanation in2 to 3 weeks

look at the Recovery Rebate Credit Worksheet in Turbotax

Did you receive the full amount for both the first 2 Stimulus payments?  Better check your 1040 line 30 and see if an amount is listed.  That's been a common problem.  You might have answered the Stimulus questions wrong and tried to claim  it again or some more on line 30.  So the IRS took it off because you already got it.  They know they sent it to you.

1800 was the amount for the first 2 Stimulus payments 1200+600.  Did you already get them?  You tried to get it again on line 30.  But the IRS thinks they already sent you the 1800.  

You always owe your correct income tax.  

If TurboTax makes a mistake, the company will cover interest and penalties, but you always owe your own tax.  If you fail to report something or provide incorrect information, that is not a TurboTax mistake.  

It sounds like you failed to report your stimulus payments.  If the IRS thinks they sent the payments but you never received them, you have to trace the lost payments, rather than claiming them on your tax return.