@cvalente13
When the IRS changes the refund they will mail a letter of explanation in a couple of weeks. You can also look online for possible reasons : https://www.irs.gov/refunds
Most likely culprit is the stimulus credit ... if you entered the wrong amount that you got in advance then the return would have been incorrect and the IRS is fixing these errors automatically. Look at your form 1040 line 30.
