I an an Enrolled Agent. I get this question a lot at work.
If the IRS removed the Recovery Rebate Credit (1040 page 2 line 30) from your 2021 return and you did not get the 3rd stimulus check, the only way to get it is to call IRS Payment Trace at 1-800-919-9835 or mail form 3911.
Lots of luck. My first $1200 stimulus check was lost or stolen or mis-delivered or returned to sender. It was mailed but I never got it. I have been waiting almost two years for the results of the payment trace I put in regarding it. I have received many idiotic notices and letters contradicting each other and making ridiculous demands while the payment trace has been pending. I have resubmitted it 3 or 4 times. I don’t think I will ever get the results.
Hmmm...
I didn’t get the first one, yet the same question was on my 2020 return and resulted in a credit for 2020 with no IRS notice.
The only thing different for this year was the IRS notice of revocation of the credit and tax due (I don’t have the notice in front of me).