@jonic - it is somewhat simpler than that.
1) since you are over 60, there are no penalties for withdrawals - whether that is on the original contributions or on the earnings that occur along the way.
2) All the contributions come out first and the earnings last,
3 ) the contributions don't have to stay in for 5 years and it's after tax money in any event, so there is no tax implication (no tax no penalties, given your age) for a withdrawal no matter when it occurs
4) the earnings have to remain in the Roth for 5 years to be tax-free. But practically, that is not likely to occur (but indeed mathmatically possible). The earning from 2022 have to remain until 2027, the 2023 earnings until 2028, etc. But remember, that only becomes an issue if ALL the contributions have been withdrawn and you are withdrawing earnings. if you withdraw the earnings in less than 5 years, you'll pay ordinary tax on those withdrawn earnings, but again, no 10% penality as you are over 60.
as a side note, and you did not state you age, but note that there is a tax called "IRMAA" related to Medicare premiums. The ROTH conversions create taxable income and you'll want to assess any implications of IRMAA two tax years before you begin Medicare (so if you are going to go on Medicare in 2025, then your AGI in 2023 is going to define the IRMAA tax in 2025) as part of your conversion strategy.
