When you:
1- create a new AD user account on the source side only and set a password for that user
2- in the OD AD Template --> 'options' --> 'Password Options' have the 'Default Password For New Uses' set to be a different password..
3- do migration workflow that synced the source and target environments and wrote out that user to the target.
4- log into the target as that user with the password that had been set on the source. The password to use is the password that had been synced over, not the password set in 'Default Password For New Uses'.
User passwords get changed during a password sync. Even for users who hadn’t changed their password since this ODM tool had been configured but had pre-existing different passwords on the target tenant compared to the source tenant.
It is _not_ the case that the passwords would not be sync 'ed until the the next time the user changed the account password.