[mononcqc]

It is possible that the transaction log's last entry contains a value that is not yet considered 'committed' at large, as per the paper. This transaction needs to be confirmed later on when an additional transaction comes and supercede it, confirming it was committed by all.

It is also possible for a leader to be demoted during a split, where the log of that partial transaction will not be counted as final. The new leader at this point can then force a truncation of a follower's log, or ignore it entirely.

The entry you have read from a node that was thought to still be a master without first consulting a majority is therefore possibly a bad write that won't be part of history as far as consensus goes.

This is explained later in the original Raft paper, and this is why you need to read from the quorum to be able to guarantee consistency under all circumstances, among other problem cases.