The most recent Orion RC has broken the iCloud Passwords Extension (I have the Firefox version installed).
Upon starting Orion RC and clicking the iCloud Passwords icon in the menu bar you can authenticate fine and activate the extension however it does not offer any passwords when you navigate to a login page.
i have attached screenshots from the latest Orion RC (no login information offerred) and the latest Orion Beta (extension works fine).
iCloud Password extension works as designed and offers passwords on login pages.
Version 0.99.131.2-rc (WebKit 621.1.2.111.4)
Sequoia (15)