During recovery, we assume the oplogApplicationStartPoint (which derives from the stable timestamp)
https://github.com/mongodb/mongo/blob/2c446f3f587f406c23cdfca87f227ee5cd466fa8/src/mongo/db/repl/replication_recovery.cpp#L165

After the PM-1713
Remove Stable Optime Candidates List project, this is no longer the case. If the oplogApplicationStartPoint is not present in the oplog, that's OK. In this case we must apply every entry in the oplog query (i.e. we do NOT skip the first entry)

It is also the case that the oplog query may return no oplog entries, so the check here

https://github.com/mongodb/mongo/blob/2c446f3f587f406c23cdfca87f227ee5cd466fa8/src/mongo/db/repl/replication_recovery.cpp#L149

is also incorrect and should be replaced with a log message.