The IRS must think they sent it to you.
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.
Double check your bank statements and Check your IRS account to see when and what they sent you (check both spouse's accounts if married)
Your Online Account | Internal Revenue Service
Request a trace for a missing third Stimulus payment
https://www.irs.gov/newsroom/questions-and-answers-about-the-third-economic-impact-payment-topic-j-p...Your Online Account | Internal Revenue Service
