What the marsh does to a wall
Marsh-front elevations on Daniel Island get a combination almost nothing else in the Lowcountry gets: constant salt aerosol, long humid stretches with no drying wind, and wind-driven rain arriving flat rather than falling. Cedar handles two of those. It does not handle all three at once with no drainage plane behind it.
The tell was the paint. It was lifting in sheets rather than chalking, which means moisture was pushing out from behind the coating instead of UV breaking it down from the front. That reads as a water management problem, not a paint problem, and repainting would have bought about eighteen months.