Your test does duplicate what would happen when jamming takes place because the communication between homebase and cameras is broken. The battery cams like 2C don’t have any local storage, so if they can’t talk to the homebase, for any reason, the event can’t be saved.
I think the support person doesn’t really understand how the Eufy devices communicate. They are saying that if your homebase to router connection is done via ethernet, you won’t be subject to jamming. That’s not true. Any jamming on the 2.4 Ghz band will interfere with the camera to homebase connection unless its very narrow band. Your homebase can still talk to the internet via ethernet to the router, but can’t get through the blanket of noise put up by the jammers to talk to the cameras. If your router is connected to homebase via wifi, then you get a double whammy as the jammer will kill both sides of the homebase connection.
If you have discerning thieves, they can use a spectrum analyzer to find the frequencies that your security system is using and then just blanket a single channel. Most of them will just use a jammer that takes out the whole band.