SmartScreen is not Windows Defender, the latter is the antivirus with its own regularly updated database, firewall, etc.

SmartScreen basically sends your files to Microsoft, for "enhanced security" or something.

FWIW I put Defender on notification only mode because Microsoft ever so helpfully removed the actual quarantine directory and now files dumped into quarantine are basically unrecoverable.

I just use the firewall with a third party interactive GUI and block anything that I can't identify.