In disagg, when building delta with prepared updates, the following situation can cause us missing an update in the delta:

• Initially we write update U to the data store and we mark it with the WT_UPDATE_DURABLE flag.
• We do a prepared update Up. Now we have Up -> U on the update chain.
• We rollback the prepared update.
• However, the rollback timestamp is not stable and we still write Up to the data store and U to the history store.
• The rollback timestamp becomes stable and this time we skip Up and skip U as well when building the delta because it already has the WT_UPDATE_DURABLE flag on it.