EAD renew: Request for Evidence

My EAD expires one Month later. Today received an email notice from USCIS, "we mailed a notice requesting additional evidence or information in this case I765 APPLICATION FOR EMPLOYMENT AUTHORIZATION."

It makes me nervous.I changed my job during this period, same category, didn't file AC-21.

1. Not sure I can make it in one Month.

2. What kind of evidence they need.

3. Since I didn't file AC21 after I changed my job (this is the second time I changed job after received EAD), will this be a factor?

Any suggeston will be very helpful

Thanks