Did any sitter get an email from Rover.com accounting regarding audit?

Nope. It sounds like a phishing attempt. Do not respond to it. Don't click on anything.

No accountant or auditor would correspond via email in an official capacity. If you want to verify, I would suggest calling Rover Customer Support at [Edit: Rover’s contact options have changed. Visit the Rover Help Center at https://support.rover.com/ to find the phone number, help articles, or chat with the team].