https://www.bleepingcomputer.com/news/security/android-bug-leaks-dns-queries-even-when-vpn-kill-switch-is-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.