Retirement tax questions

I got the 1099-R this year because in 2021 I rolled over after tax money that was in my 401k into a ROTH IRA.  I already paid taxes on this money years ago and it was sitting in my 401k as I over contributed at some point.  Box 7 code on my form is also G.  Why is TurboTax asking me about the source of my Distribution if I do not need to pay taxes on this moneys?