I had one in '22, ('21 return), refund was approx 4,500.00. Less than 10 days after e-filing, they had a direct deposit of 1,528.43. The timing, and amount, led us both to believe it was for something else - ID theft, previous year, etc. No explanation could be found and no other money was received in the "refund" window.
Eight or ten months later, they received a direct deposit that made the total equal 4,500.00 + interest. (Subsequent 1099 from Treasury confirmed this.) To date, there has been no correspondence, (explanation), from the IRS.