Interesting. Not for me.
I have an iPhone with a WireGuard tunnel back to my house. When connected just on cellular, SpeedTest says my mobile provider for the connection.
When I connect to VPN and try again, it says my home ISP provider and doesn’t mention the mobile part at all.








In your original reply, you cite the app as smart enough to know the mobile ISP even with VPN on, and it shows this to you in the app, yet that is not my experience. If it were as you say, shouldn’t my app still say my mobile ISP even with the VPN active?
Maybe you are running a split tunnel or something? When I’m on VPN over mobile, it’s the same as running the test on my home wifi.
EDIT: we could also be talking about different parts of the app. As I dug further into this, the main page that just shows your speed, connection, and test server work/look the same for me on VPN on mobile or WiFi, showing my home ISP. However, I did discover that if I go into the detailed results page, it shows that I was using a mobile connection and doesn’t show my home ISP name at all. Very curious.
EDIT2: last edit — tests over mobile on VPN in detailed results show my home ISP IP as the egress point, so one should be able to determine if their VPN is effective that way.