Could it be for state refund? Federal and state refunds come separately at different times from different places. If the IRS adjusted your return and sent you less they will mail you a letter explaining what they changed. You have to ask the IRS .
What does the IRS say at Where’s My Refund for how much they sent you?
https://www.irs.gov/refunds
Probably the IRS found something with your return. You can call them to find out or wait until they send you an explanation in 2 to 3 weeks
1. Call 1-800-829-1040 between the hours of 7:00 AM – 7:00 PM local time.
2. Press “1” for English or “2” for Spanish.
3. Press “2” for “answers about your personal income taxes.”
4. Press “1” for “questions about a form you have already submitted or a payment or to order a tax transcript.”
5. Press “3” for “all other questions about your tax history or payment.”
6. Press “2” for “all other questions about your tax history or payment.”
7. Do not input your Social Security Number when the recording tells you to.
8. Press “2” for “personal- or individual-tax related question.”
9. Press “3” for “all other inquiries.”
10. Wait to be connected to someone at the IRS.