Thanks for the report.
Jetpack uses wp_generate_password, that generates unique numbers to use to create nonces. That's the request you see in your database.
That doesn't explain why this would happen 28 times per page load, though.
I've created a GitHub issue here and we'll look into the problem and get this fixed. Feel free to subscribe to follow our discussion.
Could you confirm that you run the latest version of Jetpack and WordPress? What other plugins are currently active on these sites?
Thanks!