FaceTime video/audio broken by Private Internet Access VPN client on Mac

For about a year FaceTime on my MacBook "connected" fine, the call would ring, both sides would say Connected, but neither side saw video or heard audio. It would just show each user’s initials in circles.

After some debugging with Claude (agents turn out to be great at this sort of thing) I tracked it down to Private Internet Access’s client which includes a SplitTunnelProxyExtension system extension for intercepting traffic.

The fix: System Settings → General → Login Items & Extensions → Network Extensions → toggle SplitTunnelProxyExtension off.

After that FaceTime worked correctly.

It looks like technically this is not a PIA bug, but known Apple bug in NETransparentProxyProvider.