Why does my new GE phone App connect to other GE inverter

I recently visited a relative who also has GE inverter and batteries. My phone automatically connects to his router so I can use his wifi when there.
I showed him the new free GE app (Not Premium version) on my phone and to my surprise it was showing full data from his installation. I assume I could have altered his settings.
Now when at home the app shows two inverter serial numbers. If I had cloud access could I then read/adjust his inverter?
Is this a security issue?

I dont think it will do anything to his inverter if you are not on the same network which you will not be when you are at your house.
You are on the free version "connect via cloud server" button will not work
If you paid for premium and used the cloud server (i doubt), but cannot confirm that it would connect to his inverter.
I am no expert and your observation is interesting. I suspect others will know more than me.

Yes, it's a big issue. Little Johnny will have a field day. Unfortunately for Grandad, Giv software don't have any money and aren't worth suing.
https://givenergymonitor.co.uk/controls.html

Perhaps your friend should setup a guest network and then you would not be able to "see" his inverter

IGremlin GE never put any authentication controls into the inverter. So anyone who is on the same ip subnet as the inverter could read and write to the inverter. This is why it is important to keep your inverter on its own subnet and to ensure that if you use WiFi that it is secured to prevent say your neighbours from jumping on the WiFi. The previous GE app relied on you authenticating to the cloud and you read and wrote data to/from the inverter via the cloud. But the new app no longer does that and takes advantage of their lack of local inverter security controls to give you local read/write access without the need to log in.
Now I don’t know what would happen if you had premium access and logged in from your app, now that it has details of an inverter you don’t own. I would hope that when you logged in with your credentials that the cloud would only give you access to your inverter’s data as that is the one registered to you. Or does anyone know otherwise ?