Recovery Rebate Credit?

I used Turbotax Form 1040SR to file my 2021 taxes, filled in all the blanks as required and would up with a refund of $547.  After waiting many months I got a return or $157.81 and a letter telling me that: "We changed the amount claimed as Recovery Rebate Credit on your tax return."  The reason given was that my adjusted gross income exceeded $75,000.  A hit of $400 was big.  Where was the mistake?