https://arstechnica.com/gadgets/2020/11/apple-lets-some-big-sur-network-traffic-bypass-firewalls/

Firewalls aren’t just for corporate networks. Large numbers of security- or privacy-conscious people also use them to filter or redirect traffic flowing in and out of their computers. Apple recently made a major change to macOS that frustrates these efforts.

Beginning with Big Sur released last week, some 50 Apple-specific apps and processes are no longer routed through firewalls like Little Snitch and Lulu. The undocumented exemption came to light only after Patrick Wardle, a security researcher at a Mac and iOS enterprise developer Jamf, disclosed the change over the weekend.