If her refund is short $1,400 then that is because she said she did not receive the 3rd stimulus payment and the IRS has records that show she was sent the 3rd stimulus payment so they removed the $1,400 Recovery Rebate Credit that was entered on Form 1040 Line 30.
Go to this IRS website for her tax account to see if the 3rd stimulus payment is entered - https://www.irs.gov/payments/your-online-account
If she checked her bank account in the March - May 2021 timeframe and there is not a $1,400 EIP3 payment from the IRS then go to this IRS website for how to start a trace on the payment - https://www.irs.gov/newsroom/questions-and-answers-about-the-third-economic-impact-payment-topic-j-p...
