Unpaid Leave of Absence - H4 EAD renewal pending - NO
There is NO official guidance from USCIS on this topic.
But, the common sense says that employer has to file form I9 for each employee and it can only be filed if you have valid work authorization in USA.
Since, your H4 EAD expires on Sep 30, starting oct 1, your I9 will be invalid without any legal work auth.
‘Leave of absence’ - Problem for employer with I9 validity
‘Leave of absence’ can place your employer in trouble as they can’t prove that you are eligible to work and still an employee on their payroll!
Terminate employment and Rejoin
So, the best option for your employer is to terminate your employment and you can rejoin once you have H4 EAD renewal CARD in your hand.