Apple's apps bypass firewalls like LittleSnitch and LuLu on macOS Big Sur

That totally breaks my use case for Little Snitch: working tethered. When I tether my laptop it thinks it has free reign with the bandwidth and all of the little background processes can kill my data in a few minutes. With a firewall, I can grant access to only the processes that I need to get my work done.

Now, I guess I have to run some external firewall between my laptop and my phone. ... or better yet, abandon Apple.

For what it's worth, my hacky solution to this is this script which kills all the background processes that use significant bandwidth. If you're interested in how I came up with the list of processes, I can share the BitBar [1] script I wrote for monitoring per-process network usage (I wrote a small wrapper around nettop that logs to a db, which is read periodically by my BitBar script to show me the per-process usage:

    if [ $(whoami) != root ]
    then
      echo "Please run as root, not $(whoami)"
      exit
    fi

    while true
    do
      killall -9 planb 2>/dev/null && echo "$(date) - Killed planb"
      killall -9 murdockd 2>/dev/null && echo "$(date) - Killed murdockd"
      killall -9 uplink-soecks 2>/dev/null && echo "$(date) - Killed uplink"
      killall -9 nsscacheclient 2>/dev/null && echo "$(date) - Killed nsscacheclient"
      killall -9 ksfetch 2>/dev/null && echo "$(date) - Killed ksfetch"
      killall -9 nsurlsessiond 2>/dev/null && echo "$(date) - Killed nsurlsessiond"
      killall -9 softwareupdated 2>/dev/null && echo "$(date) - Killed softwareupdated"
    done

[1]: https://github.com/matryer/bitbar