@taxes96786  lol, so it sounds like “Dear TP, while preparing your 2022 returns, I noticed errors in you 2020 and 2021 returns. I am enclosing amendments that will result in additional tax on 750 for 2020 and 625 for 2021. The additional fee is $450. Please sign and return the enclosed documents and with the fee.”

You might check circular 230 for the obligations and requirements of a tax preparer. I prepare tax returns. I do not audit them.

Fwiw, I FLY a PA32/300 and subject to FARs. (Fed aviation regs.). There are many many situations where it is a physical impossibility to comply with some regs without breaking others. The trick is to do it safely.