H1B petition being sent back to USCIS for revocation

Hello, I have attended H1B interview on 30th April 2023, and I received a refusal letter (221g) from Embassy on 2nd May 2023 stating that my petition is being sent back to USCIS for revocation. They didn’t state any reason for this and they didn’t ask any extra supporting documents for review to begin with, they just sent this letter 1 month after my interview.
Can anyone please let me know what does it mean?
Why did they sent the refusal letter directly without asking for any documents?
Thank you