If you are who I think you are, we’ve probably had this discussion before. Even with an always on VPN, if the system runs out of memory it will kill the VPN first before the browser. In a perfect world the traffic would still be routed into a dead tunnel. From what I’ve seen, once the VPN is killed, the tunnel device is gone and the default route snaps back to wlan
(oh sorry, but) I’ve heard this argument before. All I can say is that in my experience, when the system is out of memory, it kills some process (e.g. the UI) which upon restarting resets the networking