--allowed-downtime-0-start=20230523170000Z --allowed-downtime-0-end=20230523170500Z --allowed-downtime-1-start=...
--allowed-downtime-start='20230523170000Z,...'
Genuine question, as I actually like the plain old flagfiles/Java-properties-ish style.
allowed-downtime[0][0] = 20230523170000Z allowed-downtime[0][1] = 20230523170500Z allowed-downtime[1][0] = ...
allowed-downtime[0].start = ...