The IRS is closed & they are not taking phone calls. They are still processing e-filed returns & stimulus checks but they have been behind.
It is taking the IRS longer to process returns since they are closed. They are still processing e-filed returns but the 21 days (business days) is not the standard now due to Covid-19. The IRS is not processing mailed in returns at this time.
You can check the IRS website, Where's My Refund, for update on your Federal refund, the website updates once a day.
https://www.irs.gov/refunds