Gatekeeper helps protect from malicious apps by not allowing install of applications that are not notarized by Apple. Gatekeeper is always on unless you disable it through the command interface. Learn more on Apple Support page.
Prevents installation and running of malware and viruses. You've probably disabled this setting if you do testing of indy apps that don't have notarization by Apple. This check reminds you to turn it back on once you're done testing.
sudo spctl --master-enableand click enter.
spctl --statusand click enter.