I have the same bug.
I just received IRS Form CP12 notifying me of an error in the Recovery Rebate Credit.
All numbers are calculated correct.
It appears TT entered a $2800 credit on 1040SR line #30.
TT did not ask if we had received stimulus checks, and apparently entered this amount.
IRS knows we received stimulus checks, so they disallowed this $2800 credit, resulting in tax due.
IMO, this is a bug in 2021 Turbo Tax.
