That would look like you filed as Married Filing Jointly with one dependent since the amount adjusted is $4,200 at $1,400 per person.
Did you indicate on your tax return that you did NOT receive the 3rd stimulus payment? If so, the IRS records show that the stimulus payment was sent to you so they adjusted your tax return accordingly.
Check you bank account for the March - May 2021 timeframe and see if there is a deposit of $4,200.
If not and you never received the stimulus payments then you can start a trace on the payment using the information in this IRS website - https://www.irs.gov/newsroom/questions-and-answers-about-the-third-economic-impact-payment-topic-j-p...
