Hi Rogp,
I have made a notarization for the Publii app before the official release. It is weird case, because I have checked it now on second mac where Publii wasn’t installed earlier and it runs properly. I have even got an information that Publii is an app downloaded from the internet and Apple didn’t detected any malicious software on it.
So I have no idea why you got your message – maybe there is some issue with the gatekeeper database sync or something else.