if you are stating that you completed the tax return and reflected that the 2nd stim payment had not arrived (which means $600 was on Line 30) but then the $600 arrived in any event, which means you are no long entitled to the $600 on your tax return, the tax return is in the audit backlog
https://www.usatoday.com/story/money/2021/04/23/stimulus-check-update-2021-tax-refund-delay-covid-re...
