I'm using the same set of connected devices in Home.app on two Macs (both on Big Sur), an iPhone and an iPad. All of a sudden, the Home app on one of the Macs prompts me to enable iCloud Keychain in order to use it (see the screenshot below). I never used iCloud Keychain, and I frankly rather wouldn't have my Keychain in the Cloud. I do use iCloud for Home.app.
The other Mac and the iDevices still work fine without iCloud Keychain, though. Is there a way to get Home.app to work as before without iCloud Keychain?