"2021 Roth IRA penalties could just be factored into 2022 year’s taxes?"

My understanding is you look at the event for Cash Basis.

Missed RMD in prior year(s) and taking it now = current year tax event (no prior year amendment) as there is no tax event in any of those prior years. Only in the year being taken.

But, your tax payer has excise tax and/or penalties, for every year that you realize these scenarios existed. That would = amendment.