IMO, it's a different issue. Ther ei no timing issue, it's reproductible in any case.
FTR, I tested it on 2.4.44 (even if the original issue was seen on 2.4.42)
The key here is really to create the replicator user before or after configuring syncrepl on the slave : if the user is created first, then all the entries get replicated from the master, and if teh user is created after the syncrepl configuration, no entry older than the moment the replicator user is added are read from the master.