VPN mode is kept on after switching off the main control

This doesn't seem to make sense from a regular user's respective - the main switch is considered a global control, so users will think about it when they want or no longer want the app's functionality, and turning something off should turn it off completely. Currently the VPN switch and the main switch are mostly independent entities, with the exception of switching on the VPN automatically activates the main switch. While the automatic activation might be useful, it's simpler and less confusing for the VPN switch to act just as a configuration toggle, where it only takes effect when the main switch is on. It might be technically not the case if tor operates independently, but it would probably be a regular user's expectation if they use the Orbot as a standalone vpn (read: censorship circumvent) app.

ps. I can only come up with using it as a kill-switch to justify the current behaviour, but Android now provides Always On VPN so advanced users should be able to use that.