Those are just generic reasons they give if they changed the Recovery rebate credit on line 30. How much is on 1040 line 30?
You must have had 600 too much on 1040 line 30. That could have been for the second Stimulus payment if you didn't already get it. Did you get both the first and second rounds? Maybe the second one came after you filed? The IRS knows they already sent it to you. But you tried to claim it again on your tax return.
If you claimed a missing stimulus payment on your return but the IRS took it off you have to ask the IRS. They think they already sent it to you. Maybe it went to an account you don't remember. Or you got a check or a card. It was probably easy to miss the debit card in the mail and think it was junk mail. They have to put a trace on it.
