Here is a very specific scenario: if there are 3 nodes (S1, S2, S3), the network is partitioned to P1 (S1 and S2 in it) and P2 (S3 in it). S1 crashed and then a fresh new S1, which forgets the latest status, snapshot, WAL logs, etc., but has the same IP and configuration, started in P2. S1 and S3 now have quorum. S3 becomes leader. The committed logs, which are in S2 but not replicated to S3 due to network partitioning, will be lost.
This is quite an unusual situation (and may not the scope of raft). I would appreciate any practical advice on how to address the durability issue.