H1-B receipt notice

I have applied for H1B extension and got my case receipt notice on dec 29 2020 but today all sudden in uscis case tracker when I checked it update the new date as Jan 15 2021 and say your case was received and has same receipt notice.

Not sure what is going on I tried to reach out the uscis customer service and started following up they said will email you further update on this issue.
I’m little worried not sure what is going could you share your experience or comment on this that may be get help for me sir.