If you're trying to open an app or installer on your Mac and seeing this error:
"App.pkg” can’t be opened because Apple cannot check it for malicious software.
That is the default warning that appears appears for any app that isn’t “notarized” by Apple — which includes many tools from small developers, open-source apps, or beta software.
Always make sure you downloaded the file from a trusted website or developer. As long as you trust the source, it’s safe to bypass.