Today it happened again and I made two screenshots. WiFi and LTE turned off, but VPN is active and connected with internet. I am not sure but I think its the data connection which stays active.
Hmmmm… interesting. For your info, I also run ProtonVPN (always auto connected by default) and when I put my phone S9+ eOS Q into airplane mode, ALL connections are paused and my ProtonVPN goes from green to orange text and says “Waiting for usable network”. Then I just clicked airplane mode to again and VPN text went back to green and “Connected”