https://www.bleepingcomputer.com/news/security/android-bug-can-leak-dns-traffic-with-vpn-kill-switch-enabled/

A Mullvad VPN user has discovered that Android devices leak DNS queries when switching VPN servers even though the "Always-on VPN" feature was enabled with the "Block connections without VPN" option.

"Always-on VPN" is designed to start the VPN service when the device boots and keep it running while the device or profile is on.