That is just the list of generic reasons they give if they changed the Recovery rebate credit on line 30. How much is on 1040 line 30? If the filed return had the wrong amount on line 30 the IRS will correct it and reduce your refund or send you a bill. You do not need to amend.
Sounds like you didn't enter the right amount of Stimulus payments you already got. Or you got the second one after you filed. The IRS adjusted your return for it. They know how much they sent you.
