@Joeyfwb - okay, I figured this out.
1) the stimulus was $1400 and you were asked in TT to enter how much you received last year. You correctly entered $1400, which is why Line 30 of Form 1040 is correctly zero. zero means you were due nothing additional (each person on your tax return was worth $1400 and you received $1400, so not due anything more). So far so good.
2) but somehow you also must have inadvertantly entered that you received $1400 for the Advance Child Tax credit which you really never received. Turbo Tax was smart enough to know that by the IRS rules, you needed to pay back the $1400 (your income level required it - there are a myriad of rules pertaining to 'payback'), so it entered $1400 as additional Tax on Form 1040 Line 23, which means your refund was $1400 lower / tax due was $1400 higher than necessary. In essence you paid back $1400 that you never received in the first place.
3) When the IRS processed your return they see that you stated you received $1400 for the Advance Child Care Credit, but the IRS could also tell from its own records that you did not receive that money, so you did not owe the 'tax' on Line 23 of Form 1040. They refunded that to you!
Cash the check!
make sense?
