Question on Social Security distribution overpayment

[Bob Malecki]

I'm collecting social security and received a letter from SSA stating that I made too much money in 2020 and they will hold back distributions to make up for payments made Jan-March 2020. So I'm trying to determine how this will work for 2021 since my 'full retirement age" was met last year on 8/31/21

Does anyone know if I'm subject to "over-earning" for 2021 up to 8/31/21 or am I essentailly exempt since I reached full retirement age in that year? 

I'm trying to figure out how this will be calculated to avoid another overpayment notice next year.