In the latest macOS 15.3 update, Apple has (again) unexpectedly removed ICMP support from the Network Extension framework used by third-party firewalls (like Little Snitch). This change means these firewalls can no longer monitor or block ICMP traffic, such as the data sent by the ping command, leaving a concerning gap in network security. This development feels like a setback, as it diminishes the ability to fully protect any macOS system.
On the other hand, it’s much easier and simpler to fully delete Little Snitch now instead of how it was before.
But yeah, hope Apple fixes this.