no log during data transfer phase (note 3070606)

Dear all,

In note 3070606 (https://launchpad.support.sap.com/#/notes/3070606), its is written :

"Unavailability of the Non-Production SAP S/4HANA Cloud System

_____o Non-Production SAP S/4HANA Cloud system will not be available during the execution of the test data refresh service

_____________ Users should not log in during the data transfer phase. All scheduled background jobs should be set on hold before data transfer commences "

I understand that this recommandation concern Q system. But still, it is not obvious to prevent users from login, especially API and interfaces :

1- Could you let me know what is the impact if a user logs during the data transfer phase ? (especially as we might miss to lock one of the API)

2- I understand that this recommandation is only for the "data transfer phase", so I guess it is NOT necessary to prevent login and background jobs... during the "completion and Handover phase". Am I correct ?

Kind regards,

Guillaume