Today, when I clicked on Save as good, SpamSieve moved messages that were in Spam to the iCloud inbox.
I see on another post that the solution would be to update to SpamSieve 2.9.47b1, but I can’t find a link to this version.
OS: Monterey 12.0.1
It sounds like it’s already working correctly for you, but if you would like to try the beta it’s available here.