Did you get a letter from the IRS?   What did it say?  Did it give any reasons?  How much is missing?

The 2 most common reasons this year is you entered the wrong amount on line 30 for the Recovery Rebate Credit (3rd Stimulus payment) or line 28 for the Child Tax Credit.  Those lines are just if you didn't already get the full amount or qualify for more.  The IRS knows what they already sent you.  

A lot of people answered the questions wrong and tried to claim the credits again.  Double check your bank statements and Check your IRS account (both accounts if married)

Your Online Account | Internal Revenue Service

I've got the same issue.  My tax return was cut in half.  The IRS says there was an issue on Schedule 8812.  I would like to understand the details around how that is possible.  When working through my taxes using your software, I only plugged in numbers as directed.

@JBURCH7 - @juju4tees  Form 8812 is the Child Tax Credit

Here is the probable issue

1) please look at Form 8812 and specifically Line 14f - this is the amount you told turbo tax you received for the Advance Child Tax Credit. Where did you get this number from? 

2) Look at you Bank account statements for the months of July - Dec, 2021.  How much did the IRS direct deposit to you? DO NOT DO THIS FROM MEMORY.  Please open all 6 bank account statements! 

If 1) and 2) are not the same (and I suspect they are not since the IRS adjusted your tax return), this should be the amount the IRS adjusted you tax return and therefore your refund by. 

make sense?