Yes and no. On the primary durability order and visibility order are different. So an async transaction that starts committing later can become visible to reade

Yes and no. On the primary durability order and visibility order are different. So an async transaction that starts committing later can become visible to readers before a sync transaction that comes before it. A read-write sync transaction that reads the result of a non-durable transaction cannot commit ahead of the async transaction. But there is no such guarantee for read-only transactions. So a transaction could read a non-durable state, decide that no further action is needed, and have that decision be invalidated by a crash/failover. To make things even worse, similar things can happen with synchronously replicated transactions. If a committing transaction waiting on replication is cancelled it will become visible immediately. A reasonably written application would run a retry of the transaction, see that the result is there and conclude that no action is necessary, even though the data is not replicated and would be lost if a failover then happens.